fix: harden SSH trust and dependency security

20260602-1221-securityAudit.md

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+# Security Audit Report
+
+## 1. Executive Summary
+
+This audit reviewed Nexus Terminal, a Wails desktop SSH/Telnet/RAW/VNC/SFTP client with a Go backend and JavaScript frontend. Fix mode was requested, so confirmed issues were patched, regression-tested, and prepared for commit.
+
+The highest-risk issues were SSH trust failures: regular SSH sessions were not wired to the existing known-host verification flow, jump-host SSH connections ignored host keys, and VNC SSH tunnels also ignored host keys. These could allow machine-in-the-middle attacks against SSH credentials and terminal/VNC traffic. This run wired all SSH paths to known-host verification and prompt handling.
+
+Other fixed issues include a local noVNC WebSocket proxy access-control weakness, SSH key-name path traversal in public-key reads, unsafe update-result DOM rendering, inline secret leakage in non-secret profile exports, and current vulnerable dependency versions in `golang.org/x/crypto` and `esbuild`.
+
+Residual risk remains in user-selected insecure modes such as direct unencrypted VNC, user-configured `HostKeyInsecure`, and large local file transfer workflows that still process complete files in memory.
+
+## 2. Scope Reviewed
+
+Reviewed:
+
+- Go backend packages under `internal/`: API bindings, sessions, SSH, VNC, SFTP, storage, secrets, updater, raw/telnet clients, recording, validation, known hosts, config, app startup.
+- Frontend JavaScript under `frontend/src/js`: settings/update UI, host-key event handling, terminal and SFTP/VNC/GitHub surfaces, common DOM helpers.
+- Dependency manifests and lockfiles: `go.mod`, `go.sum`, `frontend/package.json`, `frontend/package-lock.json`.
+- Build and release scripts: `Makefile`, `build.sh`, `release.sh`, Wails config.
+- Tests under `internal/**/*_test.go`.
+
+Not in scope:
+
+- Live network penetration testing of remote hosts.
+- Reverse engineering packaged binaries.
+- Manual verification of Wails runtime origin values in a built app.
+
+## 3. Methodology
+
+- Static source review of trust boundaries, file operations, SSH/VNC flows, Wails API bindings, frontend DOM sinks, update checks, storage, crypto, and secret handling.
+- Dependency review with `govulncheck` and `npm audit`.
+- Configuration review of Wails, build scripts, update manifests, and release paths.
+- Threat modelling of desktop renderer compromise, local web-origin attacks, remote SSH/VNC attackers, and malicious update metadata.
+- Denial-of-service review of network timeouts, WebSocket proxy behavior, transfer paths, and file ingestion.
+- Regression tests added for fixed Go issues.
+
+## 4. Risk Rating Method
+
+Severity considered exploitability, attacker position, affected security property, and impact:
+
+- Critical: practical remote compromise or credential disclosure without meaningful preconditions.
+- High: credential/session compromise or machine-in-the-middle exposure on primary connection paths.
+- Medium: meaningful local, renderer, or network-assisted exploit with constraints.
+- Low: hardening issue, local DoS, or user-assisted exposure.
+- Informational: checked area or non-security note.
+
+Confidence reflects direct code evidence and verification coverage.
+
+## 5. Findings Summary Table
+
+| ID | Severity | Confidence | Title | Component | Status |
+|---|---:|---:|---|---|---|
+| SEC-001 | High | High | SSH sessions and jump hosts bypassed known-host verification | SSH sessions | Fixed |
+| SEC-002 | High | High | VNC SSH tunnels accepted any SSH host key | VNC over SSH | Fixed |
+| SEC-003 | Medium | High | Local noVNC WebSocket proxy used a guessable root endpoint | VNC WebSocket proxy | Fixed |
+| SEC-004 | Medium | High | SSH public-key read accepted traversal key names | SSH key API | Fixed |
+| SEC-005 | Medium | High | Update metadata rendered through dynamic HTML and inline handler | Settings/update UI | Fixed |
+| SEC-006 | Medium | High | Non-secret profile export leaked inline SSH secrets | Profile export | Fixed |
+| SEC-007 | High | High | `golang.org/x/crypto` vulnerable in reachable SSH code | Go dependencies | Fixed |
+| SEC-008 | Medium | High | `esbuild` dev dependency matched current npm advisory | Frontend dependency | Fixed |
+| SEC-009 | Low | Medium | Large local file upload paths remain memory-heavy | File transfer UX | Open |
+| SEC-010 | Low | Medium | Direct VNC remains unencrypted by protocol choice | VNC direct mode | Open |
+
+## 6. Detailed Findings
+
+### Finding ID: SEC-001
+
+#### Title
+
+SSH sessions and jump hosts bypassed known-host verification
+
+#### Severity
+
+High
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `internal/sessions/manager.go`, SSH connection setup, now fixed at lines 657 and 1450-1502.
+- `internal/sshclient/sshclient.go`, jump-host config, now fixed at lines 599 and 646-652.
+- `frontend/src/js/app.js`, host-key response correlation, now fixed at lines 334-342.
+
+#### Description
+
+The project already contained known-host storage, a host-key verifier, and frontend prompt UI, but the main SSH session manager previously called the SSH client's default `Connect` path. That default path used `ssh.InsecureIgnoreHostKey()`. Jump hosts also built their own `ssh.ClientConfig` with `ssh.InsecureIgnoreHostKey()`.
+
+#### Evidence
+
+The fix now calls `ConnectWithHostKeyCallback(...)` for regular SSH sessions and propagates the final host-key callback into jump-host configs. A request ID is included in host-key prompt responses to prevent cross-session prompt confusion.
+
+#### Attack Scenario
+
+An attacker on the network path presents a fake SSH server or jump host. Without host-key verification, Nexus Terminal would accept the attacker's key, allowing credential capture, terminal tampering, or traffic interception.
+
+#### Impact
+
+Possible SSH credential theft, terminal command tampering, and loss of server authenticity.
+
+#### Recommendation
+
+Always use the known-host verifier for every SSH hop. Unknown host keys should follow the configured profile policy: strict, ask, accept-new, or explicit insecure.
+
+#### Safer Example
+
+Implemented: `Manager.hostKeyCallback` builds `sshclient.NewHostKeyVerifier(...)`, emits a prompt when needed, and `connectSSH` calls `ConnectWithHostKeyCallback(...)`.
+
+#### Suggested Tests
+
+Added regression coverage:
+
+- `TestHostKeyCallbackAcceptNewStoresHost`
+- `TestHostKeyCallbackStrictRejectsUnknownHost`
+- `TestJumpHostClientConfigUsesFinalHostKeyCallback`
+
+#### References
+
+- CWE-295: Improper Certificate Validation, analogous host-key trust failure.
+- OWASP ASVS 9.1.2: server certificate validation principles.
+
+#### Assumptions / Limitations
+
+Profiles may still explicitly choose `HostKeyInsecure`; that is a user-selected insecure mode and remains visible as residual risk.
+
+### Finding ID: SEC-002
+
+#### Title
+
+VNC SSH tunnels accepted any SSH host key
+
+#### Severity
+
+High
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `internal/vncclient/vncclient.go`, VNC SSH config, now fixed at lines 49 and 89-95.
+- `internal/sessions/manager.go`, VNC SSH callback wiring, now fixed at line 1016.
+
+#### Description
+
+VNC SSH tunnels established SSH connections with `ssh.InsecureIgnoreHostKey()`, allowing a network attacker to impersonate the SSH tunnel endpoint.
+
+#### Evidence
+
+The VNC client now requires `SSHHostKeyCallback` for tunneled SSH. The session manager supplies the same known-host/prompt path used by SSH sessions.
+
+#### Attack Scenario
+
+An attacker controlling DNS, Wi-Fi, or a gateway presents a fake SSH tunnel host for VNC traffic. The prior client accepted the key and tunneled VNC traffic through the attacker.
+
+#### Impact
+
+Possible VNC credential exposure, remote desktop traffic interception, and remote interaction tampering.
+
+#### Recommendation
+
+Require known-host verification for VNC SSH tunnels and reject tunnel setup if no callback is configured.
+
+#### Safer Example
+
+Implemented: `vncclient.Connect` returns an error if `cfg.SSHHostKeyCallback` is nil, and uses the provided callback in `ssh.ClientConfig`.
+
+#### Suggested Tests
+
+Covered indirectly by session host-key callback tests and VNC package tests.
+
+#### References
+
+- CWE-295.
+- OWASP ASVS 9.1.2.
+
+#### Assumptions / Limitations
+
+VNC tunnel host-key policy defaults to ask mode because VNC profiles do not currently expose a separate host-key policy field.
+
+### Finding ID: SEC-003
+
+#### Title
+
+Local noVNC WebSocket proxy used a guessable root endpoint
+
+#### Severity
+
+Medium
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `internal/vncclient/vncclient.go`, WebSocket proxy setup, now fixed at lines 171-183 and 255-260.
+
+#### Description
+
+The local VNC WebSocket proxy listened on `127.0.0.1` with a random port, but accepted upgrades on `/` and allowed any Origin. A malicious local web page could scan localhost ports and attempt to connect to an active proxy.
+
+#### Evidence
+
+The proxy now generates a 128-bit random token and exposes only `ws://127.0.0.1:<port>/<token>` to the Wails frontend.
+
+#### Attack Scenario
+
+A user visits a malicious web page while a VNC session is active. The page scans localhost WebSocket ports and connects to the proxy endpoint, potentially reading or injecting VNC traffic.
+
+#### Impact
+
+Possible local cross-origin access to VNC session traffic if the port is discovered.
+
+#### Recommendation
+
+Require an unguessable per-session URL token and continue binding only to loopback.
+
+#### Safer Example
+
+Implemented: `newProxyToken()` uses `crypto/rand` and the proxy route is registered only at the token path.
+
+#### Suggested Tests
+
+Added `TestNewProxyTokenIsRandomHex`.
+
+#### References
+
+- CWE-346: Origin Validation Error.
+- OWASP ASVS 14.4.3: cross-origin resource restrictions.
+
+#### Assumptions / Limitations
+
+`CheckOrigin` still returns true because Wails/noVNC origin behavior needs built-app verification. The unguessable path materially reduces exposure.
+
+### Finding ID: SEC-004
+
+#### Title
+
+SSH public-key read accepted traversal key names
+
+#### Severity
+
+Medium
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `internal/api/api.go`, SSH key API, now fixed at lines 1653-1708.
+
+#### Description
+
+`GetSSHPublicKey(name)` previously built `~/.ssh/<name>.pub` directly from a renderer-provided name. Unlike key generation, it did not restrict names to simple key basenames. Names such as `../somefile` could read `~/.ssh/../somefile.pub`.
+
+#### Evidence
+
+The fix centralizes key name validation through `sshKeyPairPaths(...)`, allowing only alphanumeric characters, hyphens, and underscores.
+
+#### Attack Scenario
+
+If renderer-side JavaScript is compromised or a malicious plugin/flow can invoke the Wails API, it can request public-key contents outside the intended `.ssh` key namespace if the target path ends in `.pub`.
+
+#### Impact
+
+Local file disclosure for matching `.pub` paths under paths reachable through traversal.
+
+#### Recommendation
+
+Treat key names as basenames, not paths. Apply the same validation to generate, read, and delete operations.
+
+#### Safer Example
+
+Implemented: `GetSSHPublicKey`, `GenerateSSHKey`, and `DeleteSSHKey` now all use `sshKeyPairPaths`.
+
+#### Suggested Tests
+
+Added:
+
+- `TestSSHKeyPairPathsAcceptsSafeName`
+- `TestSSHKeyPairPathsRejectsTraversal`
+- `TestSSHKeyPairPathsRejectsNestedPath`
+
+#### References
+
+- CWE-22: Path Traversal.
+
+#### Assumptions / Limitations
+
+The API still intentionally lists and reads legitimate SSH public keys in `~/.ssh`.
+
+### Finding ID: SEC-005
+
+#### Title
+
+Update metadata rendered through dynamic HTML and inline handler
+
+#### Severity
+
+Medium
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `frontend/src/js/settings.js`, update-check UI, now fixed at lines 940-958.
+
+#### Description
+
+Update metadata from GitHub or a configured update manifest was inserted into `innerHTML`, including an inline `onclick` that interpolated `info.releaseURL`. A malicious or compromised update metadata source could inject script into the Wails renderer.
+
+#### Evidence
+
+The fix constructs DOM nodes, sets text via `textContent`, and attaches a click listener with `addEventListener`.
+
+#### Attack Scenario
+
+An attacker controlling a self-hosted update manifest returns a release URL containing a quote and JavaScript payload. The prior inline handler interpolation could execute renderer JavaScript.
+
+#### Impact
+
+Renderer code execution. In a Wails app, renderer execution can call exposed backend APIs, increasing impact.
+
+#### Recommendation
+
+Never render remote metadata through string-built HTML. Use `textContent` and event listeners.
+
+#### Safer Example
+
+Implemented in `settings.js` with `createElement`, `document.createTextNode`, and `addEventListener`.
+
+#### Suggested Tests
+
+No frontend unit harness exists. Verified with `npm run build`.
+
+#### References
+
+- CWE-79: Cross-Site Scripting.
+- OWASP ASVS 5.3: output encoding.
+
+#### Assumptions / Limitations
+
+Other static modal templates still use `innerHTML`; reviewed high-risk dynamic remote metadata paths first.
+
+### Finding ID: SEC-006
+
+#### Title
+
+Non-secret profile export leaked inline SSH secrets
+
+#### Severity
+
+Medium
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `internal/api/api.go`, Wails export wrapper, now fixed at lines 683-684.
+- `internal/storage/store.go`, storage export, now fixed at lines 356-358 and 726-738.
+
+#### Description
+
+The plain profile export path accepted `includeSecrets=false` but profiles can still contain inline `ssh.proxyPassword` and `ssh.totpSecret` fields. Those fields could be serialized despite a non-secret export request.
+
+#### Evidence
+
+The fix redacts `ProxyPassword` and `TOTPSecret` for non-secret exports in both API and storage layers.
+
+#### Attack Scenario
+
+A user creates a plain profile export believing secrets are excluded. The exported JSON contains proxy credentials or TOTP secrets that are then shared, backed up, or stored insecurely.
+
+#### Impact
+
+Credential leakage and potential 2FA bypass for affected profiles.
+
+#### Recommendation
+
+Redact inline secret fields whenever `includeSecrets=false`. Prefer encrypted export for any export that intentionally includes secrets.
+
+#### Safer Example
+
+Implemented `redactProfileSecrets(...)` in storage and API packages.
+
+#### Suggested Tests
+
+Added:
+
+- `TestExportProfilesRedactsInlineSSHSecrets`
+- `TestRedactProfileSecretsClearsInlineSSHSecrets`
+
+#### References
+
+- CWE-200: Exposure of Sensitive Information.
+- OWASP ASVS 8.3: sensitive data protection.
+
+#### Assumptions / Limitations
+
+The encrypted export path intentionally includes selected profile data and is password-protected.
+
+### Finding ID: SEC-007
+
+#### Title
+
+`golang.org/x/crypto` vulnerable in reachable SSH code
+
+#### Severity
+
+High
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `go.mod`, `golang.org/x/crypto`, now fixed at line 14.
+- `go.mod`, indirect `golang.org/x/sys`, now updated at line 45.
+- Reachable SSH code in `internal/sshclient`, `internal/vncclient`, `internal/sftpclient`.
+
+#### Description
+
+`govulncheck` reported seven reachable vulnerabilities in `golang.org/x/crypto@v0.51.0`, including SSH DoS/panic issues, FIDO/U2F security-key interaction bypass risk, and SSH agent forwarding constraint handling issues.
+
+#### Evidence
+
+`govulncheck` identified GO-2026-5033, GO-2026-5020, GO-2026-5019, GO-2026-5018, GO-2026-5017, GO-2026-5013, and GO-2026-5006 as reachable before the update. The dependency is now `v0.52.0`, and rerun output reports: "No vulnerabilities found. Your code is affected by 0 vulnerabilities."
+
+#### Attack Scenario
+
+A malicious or compromised SSH server, SSH agent, key material, or protocol peer triggers vulnerable SSH library behavior during connection, channel use, key parsing, or agent forwarding.
+
+#### Impact
+
+Possible client panic, denial of service, weakened security-key interaction, or agent forwarding constraint mishandling depending on the CVE path.
+
+#### Recommendation
+
+Keep `golang.org/x/crypto` at or above `v0.52.0` and run `govulncheck` in CI.
+
+#### Safer Example
+
+Implemented: `go get golang.org/x/crypto@v0.52.0`.
+
+#### Suggested Tests
+
+Ran `govulncheck` and `go test ./...`.
+
+#### References
+
+- https://pkg.go.dev/vuln/GO-2026-5033
+- https://pkg.go.dev/vuln/GO-2026-5020
+- https://pkg.go.dev/vuln/GO-2026-5019
+- https://pkg.go.dev/vuln/GO-2026-5018
+- https://pkg.go.dev/vuln/GO-2026-5017
+- https://pkg.go.dev/vuln/GO-2026-5013
+- https://pkg.go.dev/vuln/GO-2026-5006
+
+#### Assumptions / Limitations
+
+`govulncheck` also noted vulnerabilities in required modules that are not called by this code.
+
+### Finding ID: SEC-008
+
+#### Title
+
+`esbuild` dev dependency matched current npm advisory
+
+#### Severity
+
+Medium
+
+#### Confidence
+
+High
+
+#### Affected Files / Components
+
+- `frontend/package.json`, `esbuild`, now fixed at line 22.
+- `frontend/package-lock.json`.
+
+#### Description
+
+`npm audit` reported GHSA-67mh-4wv8-2f99 for `esbuild <=0.24.2`: any website could send requests to the dev server and read responses under affected versions.
+
+#### Evidence
+
+The frontend previously resolved `esbuild@0.24.2`. It now uses `^0.28.0`, and `npm audit --json` reports zero vulnerabilities.
+
+#### Attack Scenario
+
+During local development, a malicious website could interact with the esbuild dev server and read responses if a developer runs an affected dev server.
+
+#### Impact
+
+Possible local development data exposure.
+
+#### Recommendation
+
+Use a fixed esbuild release and keep npm audit in CI.
+
+#### Safer Example
+
+Implemented: `npm install esbuild@0.28.0`.
+
+#### Suggested Tests
+
+Ran `npm audit --json` and `npm run build`.
+
+#### References
+
+- https://github.com/advisories/GHSA-67mh-4wv8-2f99
+
+#### Assumptions / Limitations
+
+This is a devDependency, so production exploitability is lower than runtime dependencies.
+
+### Finding ID: SEC-009
+
+#### Title
+
+Large local file upload paths remain memory-heavy
+
+#### Severity
+
+Low
+
+#### Confidence
+
+Medium
+
+#### Affected Files / Components
+
+- `frontend/src/js/terminal.js`, dropped-file paste/upload flows.
+- `internal/api/api.go`, `SFTPUploadData`.
+
+#### Description
+
+Some upload paths read whole files into memory and send base64 payloads to Go before uploading. This can be expensive for very large local files.
+
+#### Evidence
+
+`SFTPUploadData` decodes the entire base64 payload before calling session upload. The frontend drag/drop paste path also reads file contents into strings.
+
+#### Attack Scenario
+
+A local user or compromised renderer submits very large files, causing high memory use and potential application unresponsiveness.
+
+#### Impact
+
+Local denial of service.
+
+#### Recommendation
+
+Add size limits for paste-as-text, prefer path-based streaming upload for large files, and surface user-facing warnings for files above a threshold.
+
+#### Safer Example
+
+Use file path streaming upload where possible and reject in-memory uploads above a configured maximum.
+
+#### Suggested Tests
+
+Add boundary tests for maximum accepted in-memory upload size and UI tests for large-file warnings.
+
+#### References
+
+- CWE-400: Uncontrolled Resource Consumption.
+
+#### Assumptions / Limitations
+
+This is primarily local/user-assisted. It was left open to avoid changing UX and transfer semantics during the security fix pass.
+
+### Finding ID: SEC-010
+
+#### Title
+
+Direct VNC remains unencrypted by protocol choice
+
+#### Severity
+
+Low
+
+#### Confidence
+
+Medium
+
+#### Affected Files / Components
+
+- `internal/vncclient/vncclient.go`, direct TCP VNC mode.
+- VNC profile settings.
+
+#### Description
+
+Direct VNC connections use raw TCP to the VNC server. VNC is commonly unencrypted unless tunneled or separately protected.
+
+#### Evidence
+
+The direct branch calls `net.DialTimeout` to the VNC endpoint. SSH tunnel mode is available and now host-key verified.
+
+#### Attack Scenario
+
+On an untrusted network, direct VNC traffic may expose screen contents or credentials depending on server configuration.
+
+#### Impact
+
+Sensitive remote desktop data exposure.
+
+#### Recommendation
+
+Warn users before direct VNC connections and prefer SSH tunnel mode by default.
+
+#### Safer Example
+
+Default new VNC profiles to SSH tunnel where feasible, or show an explicit "unencrypted direct VNC" warning.
+
+#### Suggested Tests
+
+Add UI tests that direct VNC profiles show a warning before connection.
+
+#### References
+
+- OWASP ASVS 9.1: communications security.
+
+#### Assumptions / Limitations
+
+Some VNC servers may provide their own encryption; this audit did not test remote server configurations.
+
+## 7. Denial-of-Service Review
+
+Fixed:
+
+- Updated `golang.org/x/crypto` to resolve reachable SSH panic/deadlock/DoS vulnerabilities.
+- Added random-token access control to the local VNC WebSocket proxy, reducing local cross-origin abuse.
+
+Reviewed and not changed:
+
+- HTTP clients for GitHub and update checks use finite timeouts.
+- SSH/Telnet/RAW connection setup uses timeouts.
+- VNC WebSocket bridge is intentionally long-lived and uses no read/write timeout.
+- Large in-memory file upload/paste paths remain a local DoS risk; see SEC-009.
+
+## 8. Dependency and Supply-Chain Review
+
+Checks run:
+
+- `govulncheck`: fixed reachable `golang.org/x/crypto` vulnerabilities by updating to `v0.52.0`; rerun found zero reachable vulnerabilities.
+- `npm audit --json`: fixed `esbuild` advisory by updating to `0.28.0`; rerun found zero vulnerabilities.
+- `npm run build`: passed after dependency update.
+
+Notes:
+
+- `xterm` packages are deprecated upstream in favor of `@xterm/*`, but no current audit advisory was reported in this run.
+- `go.mod` still has transitive modules with vulnerabilities that `govulncheck` reports as not called by this code.
+
+## 9. Secrets and Sensitive Data Review
+
+Fixed:
+
+- Non-secret profile export now redacts inline `ProxyPassword` and `TOTPSecret`.
+- SSH host-key verification now protects credential submission from basic MITM paths.
+
+Reviewed:
+
+- Vault uses Argon2id and AES-256-GCM with random salts/nonces.
+- Vault file is written with `0600` permissions and store directories with `0700`.
+- OS keychain is preferred where available.
+
+Residual:
+
+- Secret values still exist in process memory while sessions need them.
+- Proxy password is still present in profile model state when entered inline.
+
+## 10. Authentication and Authorisation Review
+
+Fixed:
+
+- SSH, jump host, and VNC-over-SSH authentication now has host authenticity checks before credential use.
+- SSH host-key prompt responses are request-correlated.
+
+Reviewed:
+
+- SSH/TOTP flows use profile-specific secret callbacks.
+- Agent forwarding is explicit profile configuration.
+- Known-host policies include strict, ask, accept-new, and insecure.
+
+Residual:
+
+- `HostKeyInsecure` remains available for user-selected insecure connections.
+
+## 11. Input Validation and Output Encoding Review
+
+Fixed:
+
+- SSH key names now reject traversal and nested path separators.
+- Update metadata is rendered with DOM APIs instead of string-built HTML.
+- Non-secret export redacts inline secret fields.
+
+Reviewed:
+
+- SQL operations use parameterized queries.
+- Profile validation checks host, port, username, protocol-specific fields, and port-forwarding basics.
+- Frontend frequently uses `textContent` or `escapeHtml`; remaining `innerHTML` static templates should still be reviewed during future frontend hardening.
+
+## 12. Infrastructure and Deployment Review
+
+Reviewed:
+
+- Wails app binds Go services directly to the renderer. This makes frontend XSS more impactful than in a browser-only app.
+- Build scripts use `set -euo pipefail`.
+- Update checking is opt-in and does not auto-install binaries.
+
+Residual:
+
+- No CI configuration was present in the reviewed file list, so dependency scanning is not currently enforced by repository automation.
+
+## 13. Logging, Monitoring, and Error Handling Review
+
+Reviewed:
+
+- Audit logger records profile create/update/delete, connection events, secret access, import/export.
+- Errors are generally returned to the frontend with enough context for troubleshooting.
+
+Residual:
+
+- Some error messages include file paths, which is acceptable for a local desktop tool but should be considered if telemetry is later added.
+
+## 14. Test Coverage and Security Regression Gaps
+
+Added tests:
+
+- API SSH key path validation and export redaction.
+- Session host-key callback storage and strict rejection behavior.
+- Jump-host host-key callback propagation.
+- Storage export redaction.
+- VNC proxy token generation.
+
+Remaining gaps:
+
+- No frontend unit test harness for DOM injection regressions.
+- No integration test for full Wails host-key prompt round trip.
+- No VNC WebSocket integration test verifying token-only connection behavior.
+- No large-file upload boundary tests.
+
+## 15. Prioritised Remediation Plan
+
+Immediate:
+
+- Keep the fixes in this audit and ensure they are merged.
+- Add dependency scanning to CI: `govulncheck ./...` and `npm audit --audit-level=moderate`.
+
+Short-term:
+
+- Add a frontend test harness for update UI and other dynamic DOM surfaces.
+- Add direct VNC warning UX and default to SSH tunnel where possible.
+- Add explicit in-memory upload size limits.
+
+Medium-term:
+
+- Expose host-key policy for VNC SSH tunnels instead of always using ask mode.
+- Review all Wails-exposed methods under a compromised-renderer threat model.
+- Migrate deprecated `xterm` packages to maintained `@xterm/*` packages.
+
+Long-term:
+
+- Consider capability gating or confirmation for high-risk renderer-callable APIs such as file deletion, SSH key deletion, local shell selection, and profile import/export.
+- Add signed update metadata if self-hosted update manifests become a production channel.
+
+## 16. False Positives / Needs Manual Verification
+
+- Wails/noVNC Origin behavior in a packaged app should be manually verified. Tokenized VNC WebSocket paths are in place, but Origin policy may still be tightened later.
+- Direct VNC encryption depends on remote VNC server configuration and network placement.
+- `HostKeyInsecure` is intentionally user-configurable; confirm UI wording makes the risk clear.
+- Large-file memory usage thresholds need product decisions before enforcement.
+
+## 17. Final Notes
+
+Fix mode completed with code changes, tests, and dependency updates. The strongest residual concern is the general Wails threat model: a frontend XSS can call powerful local backend APIs. This audit fixed the confirmed dynamic update UI injection path and several backend trust-boundary issues, but future work should continue reducing string-built HTML and adding capability checks around sensitive local operations.

frontend/package-lock.json

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     },
     "node_modules/@esbuild/win32-x64": {
-      "version": "0.24.2",
+      "version": "0.28.0",
-      "resolved": "https://registry.npmjs.org/@esbuild/win32-x64/-/win32-x64-0.24.2.tgz",
+      "resolved": "https://registry.npmjs.org/@esbuild/win32-x64/-/win32-x64-0.28.0.tgz",
-      "integrity": "sha512-7VTgWzgMGvup6aSqDPLiW5zHaxYJGTO4OokMjIlrCtf+VpEL+cXKtCvg723iguPYI5oaUNdS+/V7OU2gvXVWEg==",
+      "integrity": "sha512-pEl1bO9mfAmIC+tW5btTmrKaujg3zGtUmWNdCw/xs70FBjwAL3o9OEKNHvNmnyylD6ubxUERiEhdsL0xBQ9efw==",
       "cpu": [
         "x64"
       ],
@@ -452,9 +469,9 @@
       "license": "MPL-2.0"
     },
     "node_modules/esbuild": {
-      "version": "0.24.2",
+      "version": "0.28.0",
-      "resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.24.2.tgz",
+      "resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.28.0.tgz",
-      "integrity": "sha512-+9egpBW8I3CD5XPe0n6BfT5fxLzxrlDzqydF3aviG+9ni1lDC/OvMHcxqEFV0+LANZG5R1bFMWfUrjVsdwxJvA==",
+      "integrity": "sha512-sNR9MHpXSUV/XB4zmsFKN+QgVG82Cc7+/aaxJ8Adi8hyOac+EXptIp45QBPaVyX3N70664wRbTcLTOemCAnyqw==",
       "dev": true,
       "hasInstallScript": true,
       "license": "MIT",
@@ -465,31 +482,32 @@
         "node": ">=18"
       },
       "optionalDependencies": {
-        "@esbuild/aix-ppc64": "0.24.2",
+        "@esbuild/aix-ppc64": "0.28.0",
-        "@esbuild/android-arm": "0.24.2",
+        "@esbuild/android-arm": "0.28.0",
-        "@esbuild/android-arm64": "0.24.2",
+        "@esbuild/android-arm64": "0.28.0",
-        "@esbuild/android-x64": "0.24.2",
+        "@esbuild/android-x64": "0.28.0",
-        "@esbuild/darwin-arm64": "0.24.2",
+        "@esbuild/darwin-arm64": "0.28.0",
-        "@esbuild/darwin-x64": "0.24.2",
+        "@esbuild/darwin-x64": "0.28.0",
-        "@esbuild/freebsd-arm64": "0.24.2",
+        "@esbuild/freebsd-arm64": "0.28.0",
-        "@esbuild/freebsd-x64": "0.24.2",
+        "@esbuild/freebsd-x64": "0.28.0",
-        "@esbuild/linux-arm": "0.24.2",
+        "@esbuild/linux-arm": "0.28.0",
-        "@esbuild/linux-arm64": "0.24.2",
+        "@esbuild/linux-arm64": "0.28.0",
-        "@esbuild/linux-ia32": "0.24.2",
+        "@esbuild/linux-ia32": "0.28.0",
-        "@esbuild/linux-loong64": "0.24.2",
+        "@esbuild/linux-loong64": "0.28.0",
-        "@esbuild/linux-mips64el": "0.24.2",
+        "@esbuild/linux-mips64el": "0.28.0",
-        "@esbuild/linux-ppc64": "0.24.2",
+        "@esbuild/linux-ppc64": "0.28.0",
-        "@esbuild/linux-riscv64": "0.24.2",
+        "@esbuild/linux-riscv64": "0.28.0",
-        "@esbuild/linux-s390x": "0.24.2",
+        "@esbuild/linux-s390x": "0.28.0",
-        "@esbuild/linux-x64": "0.24.2",
+        "@esbuild/linux-x64": "0.28.0",
-        "@esbuild/netbsd-arm64": "0.24.2",
+        "@esbuild/netbsd-arm64": "0.28.0",
-        "@esbuild/netbsd-x64": "0.24.2",
+        "@esbuild/netbsd-x64": "0.28.0",
-        "@esbuild/openbsd-arm64": "0.24.2",
+        "@esbuild/openbsd-arm64": "0.28.0",
-        "@esbuild/openbsd-x64": "0.24.2",
+        "@esbuild/openbsd-x64": "0.28.0",
-        "@esbuild/sunos-x64": "0.24.2",
+        "@esbuild/openharmony-arm64": "0.28.0",
-        "@esbuild/win32-arm64": "0.24.2",
+        "@esbuild/sunos-x64": "0.28.0",
-        "@esbuild/win32-ia32": "0.24.2",
+        "@esbuild/win32-arm64": "0.28.0",
-        "@esbuild/win32-x64": "0.24.2"
+        "@esbuild/win32-ia32": "0.28.0",
+        "@esbuild/win32-x64": "0.28.0"
       }
     },
     "node_modules/xterm": {

frontend/package.json

@@ -19,6 +19,6 @@
     "xterm-addon-web-links": "0.9.0"
   },
   "devDependencies": {
-    "esbuild": "^0.24.0"
+    "esbuild": "^0.28.0"
   }
 }

frontend/src/js/app.js

@@ -332,11 +332,13 @@
             payload.fingerprint,
           );
           window.runtime.EventsEmit("session:hostkey:response", {
+            requestID: payload.requestID,
             sessionID: payload.sessionID,
             accepted,
           });
         } catch (_) {
           window.runtime.EventsEmit("session:hostkey:response", {
+            requestID: payload.requestID,
             sessionID: payload.sessionID,
             accepted: false,
           });

frontend/src/js/settings.js

@@ -937,11 +937,29 @@
               this.app.setUpdateInfo(info);
             }
             if (info.available) {
-              resultEl.innerHTML =
+              resultEl.textContent = "";
-                `<span style="color:var(--accent)">Update available: <strong>${info.latestVersion}</strong></span>` +
+              const updateText = createElement("span");
-                (info.releaseURL
+              updateText.style.color = "var(--accent)";
-                  ? ` — <a href="#" onclick="window.runtime.BrowserOpenURL('${info.releaseURL}');return false;" style="color:var(--accent)">View release</a>`
+              updateText.appendChild(document.createTextNode("Update available: "));
-                  : "");
+              const versionText = createElement("strong");
+              versionText.textContent = String(info.latestVersion || "");
+              updateText.appendChild(versionText);
+              resultEl.appendChild(updateText);
+              if (info.releaseURL) {
+                resultEl.appendChild(document.createTextNode(" - "));
+                const releaseLink = createElement("a", "", {
+                  href: "#",
+                  textContent: "View release",
+                });
+                releaseLink.style.color = "var(--accent)";
+                releaseLink.addEventListener("click", (e) => {
+                  e.preventDefault();
+                  if (window.runtime && window.runtime.BrowserOpenURL) {
+                    window.runtime.BrowserOpenURL(String(info.releaseURL));
+                  }
+                });
+                resultEl.appendChild(releaseLink);
+              }
             } else {
               resultEl.textContent = "You are running the latest version.";
             }

go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/pquerna/otp v1.5.0
 	github.com/wailsapp/wails/v2 v2.12.0
 	github.com/zalando/go-keyring v0.2.8
-	golang.org/x/crypto v0.51.0
+	golang.org/x/crypto v0.52.0
 	golang.org/x/net v0.54.0
 	golang.org/x/text v0.37.0
 )
@@ -42,5 +42,5 @@ require (
 	github.com/valyala/fasttemplate v1.2.2 // indirect
 	github.com/wailsapp/go-webview2 v1.0.23 // indirect
 	github.com/wailsapp/mimetype v1.4.1 // indirect
-	golang.org/x/sys v0.44.0 // indirect
+	golang.org/x/sys v0.45.0 // indirect
 )

go.sum

@@ -84,6 +84,8 @@ github.com/zalando/go-keyring v0.2.8 h1:6sD/Ucpl7jNq10rM2pgqTs0sZ9V3qMrqfIIy5YPc
 github.com/zalando/go-keyring v0.2.8/go.mod h1:tsMo+VpRq5NGyKfxoBVjCuMrG47yj8cmakZDO5QGii0=
 golang.org/x/crypto v0.51.0 h1:IBPXwPfKxY7cWQZ38ZCIRPI50YLeevDLlLnyC5wRGTI=
 golang.org/x/crypto v0.51.0/go.mod h1:8AdwkbraGNABw2kOX6YFPs3WM22XqI4EXEd8g+x7Oc8=
+golang.org/x/crypto v0.52.0 h1:RMs7fP2rXdep0CftQlK8Uf+kibLm7qkCcradZWYz988=
+golang.org/x/crypto v0.52.0/go.mod h1:1QgfPxDqh0T2M/elOJtp9RvuR95kVjir0e6/BvEmGbc=
 golang.org/x/net v0.0.0-20210505024714-0287a6fb4125/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.54.0 h1:2zJIZAxAHV/OHCDTCOHAYehQzLfSXuf/5SoL/Dv6w/w=
 golang.org/x/net v0.54.0/go.mod h1:Sj4oj8jK6XmHpBZU/zWHw3BV3abl4Kvi+Ut7cQcY+cQ=
@@ -93,6 +95,8 @@ golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.44.0 h1:ildZl3J4uzeKP07r2F++Op7E9B29JRUy+a27EibtBTQ=
 golang.org/x/sys v0.44.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/sys v0.45.0 h1:dO4czNzziLiiXplLQgBCEpCvXQ3dnkn0SdaZSYdQ+FY=
+golang.org/x/sys v0.45.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.43.0 h1:S4RLU2sB31O/NCl+zFN9Aru9A/Cq2aqKpTZJ6B+DwT4=
 golang.org/x/term v0.43.0/go.mod h1:lrhlHNdQJHO+1qVYiHfFKVuVioJIheAc3fBSMFYEIsk=

internal/api/api.go

@@ -680,6 +680,9 @@ func (s *Service) ExportProfiles(includeSecrets bool) (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("failed to list profiles for export: %w", err)
 	}
+	if !includeSecrets {
+		profiles = redactProfileSecrets(profiles)
+	}
 
 	data, err := json.MarshalIndent(profiles, "", "  ")
 	if err != nil {
@@ -1604,28 +1607,17 @@ func (s *Service) ListSSHKeyPairs() ([]SSHKeyInfo, error) {
 
 // GenerateSSHKey generates a new SSH key pair.
 func (s *Service) GenerateSSHKey(name string, keyType string, bits int, passphrase string) error {
-	if name == "" {
+	keyPath, _, err := sshKeyPairPaths(name)
-		return fmt.Errorf("key name is required")
-	}
-	// Sanitise name — only allow alphanumeric, hyphens, underscores
-	for _, ch := range name {
-		if !((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '-' || ch == '_') {
-			return fmt.Errorf("key name contains invalid characters (use alphanumeric, hyphens, underscores)")
-		}
-	}
-
-	home, err := os.UserHomeDir()
 	if err != nil {
-		return fmt.Errorf("unable to determine home directory: %w", err)
+		return err
 	}
-	sshDir := filepath.Join(home, ".ssh")
+	sshDir := filepath.Dir(keyPath)
 
 	// Ensure .ssh directory exists
 	if err := os.MkdirAll(sshDir, 0700); err != nil {
 		return fmt.Errorf("unable to create .ssh directory: %w", err)
 	}
 
-	keyPath := filepath.Join(sshDir, name)
 	// Check if key already exists
 	if _, err := os.Stat(keyPath); err == nil {
 		return fmt.Errorf("key %q already exists", name)
@@ -1659,11 +1651,10 @@ func (s *Service) GenerateSSHKey(name string, keyType string, bits int, passphra
 
 // GetSSHPublicKey returns the content of a public key file.
 func (s *Service) GetSSHPublicKey(name string) (string, error) {
-	home, err := os.UserHomeDir()
+	_, pubPath, err := sshKeyPairPaths(name)
 	if err != nil {
-		return "", fmt.Errorf("unable to determine home directory: %w", err)
+		return "", err
 	}
-	pubPath := filepath.Join(home, ".ssh", name+".pub")
 	data, err := os.ReadFile(pubPath)
 	if err != nil {
 		return "", fmt.Errorf("unable to read public key: %w", err)
@@ -1673,22 +1664,9 @@ func (s *Service) GetSSHPublicKey(name string) (string, error) {
 
 // DeleteSSHKey removes an SSH key pair.
 func (s *Service) DeleteSSHKey(name string) error {
-	if name == "" {
+	privPath, pubPath, err := sshKeyPairPaths(name)
-		return fmt.Errorf("key name is required")
-	}
-	home, err := os.UserHomeDir()
 	if err != nil {
-		return fmt.Errorf("unable to determine home directory: %w", err)
+		return err
-	}
-	sshDir := filepath.Join(home, ".ssh")
-	privPath := filepath.Join(sshDir, name)
-	pubPath := privPath + ".pub"
-
-	// Verify paths are within .ssh directory (prevent directory traversal)
-	absPriv, _ := filepath.Abs(privPath)
-	absSsh, _ := filepath.Abs(sshDir)
-	if !strings.HasPrefix(absPriv, absSsh+string(os.PathSeparator)) {
-		return fmt.Errorf("invalid key name")
 	}
 
 	var errs []string
@@ -1703,3 +1681,46 @@ func (s *Service) DeleteSSHKey(name string) error {
 	}
 	return nil
 }
+
+func sshKeyPairPaths(name string) (string, string, error) {
+	keyName, err := validateSSHKeyName(name)
+	if err != nil {
+		return "", "", err
+	}
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", "", fmt.Errorf("unable to determine home directory: %w", err)
+	}
+	sshDir := filepath.Join(home, ".ssh")
+	privPath := filepath.Join(sshDir, keyName)
+	pubPath := privPath + ".pub"
+	return privPath, pubPath, nil
+}
+
+func validateSSHKeyName(name string) (string, error) {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return "", fmt.Errorf("key name is required")
+	}
+	for _, ch := range name {
+		if !((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '-' || ch == '_') {
+			return "", fmt.Errorf("key name contains invalid characters (use alphanumeric, hyphens, underscores)")
+		}
+	}
+	return name, nil
+}
+
+func redactProfileSecrets(profiles []*models.Profile) []*models.Profile {
+	redacted := make([]*models.Profile, len(profiles))
+	for i, profile := range profiles {
+		cp := *profile
+		if cp.SSH != nil {
+			sshCfg := *cp.SSH
+			sshCfg.ProxyPassword = ""
+			sshCfg.TOTPSecret = ""
+			cp.SSH = &sshCfg
+		}
+		redacted[i] = &cp
+	}
+	return redacted
+}

internal/api/api_test.go

@@ -0,0 +1,67 @@
+package api
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/andydixon/nexus/internal/models"
+)
+
+func TestSSHKeyPairPathsAcceptsSafeName(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	privPath, pubPath, err := sshKeyPairPaths("deploy_key-01")
+	if err != nil {
+		t.Fatalf("sshKeyPairPaths() error = %v", err)
+	}
+
+	wantPriv := filepath.Join(home, ".ssh", "deploy_key-01")
+	if privPath != wantPriv {
+		t.Fatalf("private path = %q, want %q", privPath, wantPriv)
+	}
+	if pubPath != wantPriv+".pub" {
+		t.Fatalf("public path = %q, want %q", pubPath, wantPriv+".pub")
+	}
+}
+
+func TestSSHKeyPairPathsRejectsTraversal(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	_, _, err := sshKeyPairPaths("../outside")
+	if err == nil {
+		t.Fatal("expected traversal key name to be rejected")
+	}
+	if !strings.Contains(err.Error(), "invalid characters") {
+		t.Fatalf("error = %q, want invalid characters", err.Error())
+	}
+}
+
+func TestSSHKeyPairPathsRejectsNestedPath(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	_, _, err := sshKeyPairPaths("nested/key")
+	if err == nil {
+		t.Fatal("expected nested key path to be rejected")
+	}
+}
+
+func TestRedactProfileSecretsClearsInlineSSHSecrets(t *testing.T) {
+	profile := models.NewProfile(models.ProtocolSSH)
+	profile.SSH.ProxyPassword = "proxy-secret"
+	profile.SSH.TOTPSecret = "totp-secret"
+
+	got := redactProfileSecrets([]*models.Profile{&profile})
+	if got[0].SSH.ProxyPassword != "" {
+		t.Fatalf("ProxyPassword = %q, want empty", got[0].SSH.ProxyPassword)
+	}
+	if got[0].SSH.TOTPSecret != "" {
+		t.Fatalf("TOTPSecret = %q, want empty", got[0].SSH.TOTPSecret)
+	}
+	if profile.SSH.ProxyPassword == "" || profile.SSH.TOTPSecret == "" {
+		t.Fatal("redaction mutated the original profile")
+	}
+}

internal/sessions/manager.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/google/uuid"
 	wailsRuntime "github.com/wailsapp/wails/v2/pkg/runtime"
+	"golang.org/x/crypto/ssh"
 
 	"github.com/andydixon/nexus/internal/audit"
 	"github.com/andydixon/nexus/internal/githubclient"
@@ -653,7 +654,7 @@ func (m *Manager) connectSSH(sess *Session, getSecret func(prompt string) (strin
 		}
 	}
 
-	if err := client.Connect(getPassword, getPassphrase); err != nil {
+	if err := client.ConnectWithHostKeyCallback(m.hostKeyCallback(sess.Info.ID, sshConf.HostKeyPolicy), getPassword, getPassphrase); err != nil {
 		return err
 	}
 
@@ -1012,6 +1013,7 @@ func (m *Manager) connectVNC(sess *Session, getSecret func(prompt string) (strin
 		cfg.SSHUsername = vncConf.SSHUsername
 		cfg.SSHAuthMethod = vncConf.SSHAuthMethod
 		cfg.SSHAgentAuth = vncConf.SSHAgentAuth
+		cfg.SSHHostKeyCallback = m.hostKeyCallback(sess.Info.ID, models.HostKeyAsk)
 
 		// Resolve SSH credentials
 		switch vncConf.SSHAuthMethod {
@@ -1445,6 +1447,60 @@ func (m *Manager) PingSession(sessionID string) (int64, error) {
 // Internal: helpers
 // ---------------------------------------------------------------------------
 
+func (m *Manager) hostKeyCallback(sessionID string, policy models.HostKeyPolicy) ssh.HostKeyCallback {
+	if policy == "" {
+		policy = models.HostKeyAsk
+	}
+	verifier := sshclient.NewHostKeyVerifier(m.store, policy)
+	verifier.SetPromptHandler(func(host string, keyType string, fingerprint string) (bool, error) {
+		return m.promptHostKey(sessionID, host, keyType, fingerprint)
+	})
+	return verifier.HostKeyCallback()
+}
+
+func (m *Manager) promptHostKey(sessionID string, host string, keyType string, fingerprint string) (bool, error) {
+	if m.ctx == nil {
+		return false, fmt.Errorf("host key prompt unavailable")
+	}
+
+	requestID := uuid.New().String()
+	ch := make(chan bool, 1)
+	cancel := wailsRuntime.EventsOn(m.ctx, "session:hostkey:response", func(optionalData ...interface{}) {
+		if len(optionalData) == 0 {
+			return
+		}
+		data, ok := optionalData[0].(map[string]interface{})
+		if !ok {
+			return
+		}
+		rid, _ := data["requestID"].(string)
+		if rid != requestID {
+			return
+		}
+		accepted, _ := data["accepted"].(bool)
+		select {
+		case ch <- accepted:
+		default:
+		}
+	})
+	defer cancel()
+
+	m.emitEvent("session:hostkey:verify", map[string]interface{}{
+		"requestID":   requestID,
+		"sessionID":   sessionID,
+		"host":        host,
+		"keyType":     keyType,
+		"fingerprint": fingerprint,
+	})
+
+	select {
+	case accepted := <-ch:
+		return accepted, nil
+	case <-time.After(5 * time.Minute):
+		return false, fmt.Errorf("host key prompt timed out")
+	}
+}
+
 // buildSecretCallback returns a func() (string, error) that resolves a
 // credential according to the profile's SecretMode:
 //   - "saved": check keychain/vault first, prompt if missing, then persist

internal/sessions/manager_test.go

@@ -1,9 +1,14 @@
 package sessions
 
 import (
+	"crypto/ed25519"
+	"crypto/rand"
+	"path/filepath"
 	"testing"
 
 	"github.com/andydixon/nexus/internal/models"
+	"github.com/andydixon/nexus/internal/storage"
+	"golang.org/x/crypto/ssh"
 )
 
 // ---------------------------------------------------------------------------
@@ -148,3 +153,61 @@ func TestCloseAllEmpty(t *testing.T) {
 		t.Error("expected 0 sessions after CloseAll")
 	}
 }
+
+func TestHostKeyCallbackAcceptNewStoresHost(t *testing.T) {
+	store := newSessionTestStore(t)
+	mgr := NewManager(store, nil, nil, nil, nil)
+	callback := mgr.hostKeyCallback("session-1", models.HostKeyAcceptNew)
+
+	key := testPublicKey(t)
+	if err := callback("jump.example:2222", nil, key); err != nil {
+		t.Fatalf("HostKeyCallback() error = %v", err)
+	}
+
+	saved, err := store.GetKnownHost("jump.example", 2222)
+	if err != nil {
+		t.Fatalf("GetKnownHost() error = %v", err)
+	}
+	if saved == nil {
+		t.Fatal("expected host key to be saved")
+	}
+	if saved.Host != "jump.example" {
+		t.Fatalf("saved host = %q, want jump.example", saved.Host)
+	}
+	if saved.Port != 2222 {
+		t.Fatalf("saved port = %d, want 2222", saved.Port)
+	}
+}
+
+func TestHostKeyCallbackStrictRejectsUnknownHost(t *testing.T) {
+	mgr := NewManager(newSessionTestStore(t), nil, nil, nil, nil)
+	callback := mgr.hostKeyCallback("session-1", models.HostKeyStrict)
+
+	err := callback("unknown.example:22", nil, testPublicKey(t))
+	if err == nil {
+		t.Fatal("expected strict policy to reject unknown host")
+	}
+}
+
+func testPublicKey(t *testing.T) ssh.PublicKey {
+	t.Helper()
+	pub, _, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatalf("GenerateKey() error = %v", err)
+	}
+	key, err := ssh.NewPublicKey(pub)
+	if err != nil {
+		t.Fatalf("NewPublicKey() error = %v", err)
+	}
+	return key
+}
+
+func newSessionTestStore(t *testing.T) *storage.Store {
+	t.Helper()
+	store, err := storage.NewStore(filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatalf("NewStore() error = %v", err)
+	}
+	t.Cleanup(func() { store.Close() })
+	return store
+}

internal/sshclient/sshclient.go

@@ -596,12 +596,7 @@ func (c *Client) connectViaJumpHosts(sc models.SSHConfig, finalConfig *ssh.Clien
 			jumpAuth = append(jumpAuth, ssh.PublicKeys(signer))
 		}
 
-		jumpConfig := &ssh.ClientConfig{
+		jumpConfig := jumpHostClientConfig(jump, jumpAuth, finalConfig)
-			User:            jump.Username,
-			Auth:            jumpAuth,
-			HostKeyCallback: ssh.InsecureIgnoreHostKey(),
-			Timeout:         finalConfig.Timeout,
-		}
 
 		if currentClient == nil {
 			client, err := ssh.Dial("tcp", jumpAddr, jumpConfig)
@@ -648,6 +643,15 @@ func (c *Client) connectViaJumpHosts(sc models.SSHConfig, finalConfig *ssh.Clien
 	return ssh.NewClient(ncc, chans, reqs), nil
 }
 
+func jumpHostClientConfig(jump models.JumpHost, auth []ssh.AuthMethod, finalConfig *ssh.ClientConfig) *ssh.ClientConfig {
+	return &ssh.ClientConfig{
+		User:            jump.Username,
+		Auth:            auth,
+		HostKeyCallback: finalConfig.HostKeyCallback,
+		Timeout:         finalConfig.Timeout,
+	}
+}
+
 // parsePrivateKey loads and parses an SSH private key file. If the key is
 // encrypted and getPassphrase is provided, it will attempt decryption.
 func (c *Client) parsePrivateKey(path string, getPassphrase func() (string, error)) (ssh.Signer, error) {

internal/sshclient/sshclient_test.go

@@ -0,0 +1,49 @@
+package sshclient
+
+import (
+	"net"
+	"testing"
+	"time"
+
+	"github.com/andydixon/nexus/internal/models"
+	"golang.org/x/crypto/ssh"
+)
+
+func TestJumpHostClientConfigUsesFinalHostKeyCallback(t *testing.T) {
+	called := false
+	hostKeyCallback := func(hostname string, _ net.Addr, _ ssh.PublicKey) error {
+		called = true
+		if hostname != "jump.example:2222" {
+			t.Fatalf("hostname = %q, want jump.example:2222", hostname)
+		}
+		return nil
+	}
+
+	finalConfig := &ssh.ClientConfig{
+		HostKeyCallback: hostKeyCallback,
+		Timeout:         12 * time.Second,
+	}
+	jump := models.JumpHost{
+		Host:     "jump.example",
+		Port:     2222,
+		Username: "alice",
+	}
+
+	got := jumpHostClientConfig(jump, nil, finalConfig)
+	if got.User != jump.Username {
+		t.Fatalf("User = %q, want %q", got.User, jump.Username)
+	}
+	if got.Timeout != finalConfig.Timeout {
+		t.Fatalf("Timeout = %s, want %s", got.Timeout, finalConfig.Timeout)
+	}
+	if got.HostKeyCallback == nil {
+		t.Fatal("HostKeyCallback is nil")
+	}
+
+	if err := got.HostKeyCallback("jump.example:2222", nil, nil); err != nil {
+		t.Fatalf("HostKeyCallback() error = %v", err)
+	}
+	if !called {
+		t.Fatal("final host key callback was not used")
+	}
+}

internal/storage/storage_test.go

@@ -3,6 +3,7 @@ package storage
 import (
 	"encoding/json"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -455,6 +456,32 @@ func TestExportProfiles(t *testing.T) {
 	}
 }
 
+func TestExportProfilesRedactsInlineSSHSecrets(t *testing.T) {
+	store := setupTestStore(t)
+	profile := makeSSHProfile("Export Secret", "secret.example.com")
+	profile.SSH.ProxyPassword = "proxy-secret"
+	profile.SSH.TOTPSecret = "totp-secret"
+	if err := store.CreateProfile(profile); err != nil {
+		t.Fatalf("CreateProfile() error = %v", err)
+	}
+
+	data, err := store.ExportProfiles(false)
+	if err != nil {
+		t.Fatalf("ExportProfiles(false) error = %v", err)
+	}
+	if strings.Contains(string(data), "proxy-secret") || strings.Contains(string(data), "totp-secret") {
+		t.Fatalf("ExportProfiles(false) leaked inline SSH secrets: %s", string(data))
+	}
+
+	data, err = store.ExportProfiles(true)
+	if err != nil {
+		t.Fatalf("ExportProfiles(true) error = %v", err)
+	}
+	if !strings.Contains(string(data), "proxy-secret") || !strings.Contains(string(data), "totp-secret") {
+		t.Fatalf("ExportProfiles(true) did not include inline SSH secrets: %s", string(data))
+	}
+}
+
 func TestImportProfiles(t *testing.T) {
 	store := setupTestStore(t)
 	p := makeSSHProfile("Import Me", "import.local")

internal/storage/store.go

@@ -346,13 +346,15 @@ func (s *Store) UpdateLastConnected(id string) error {
 }
 
 // ExportProfiles serialises all profiles as JSON. If includeSecrets is false
-// the export omits credential-related fields (currently a placeholder — all
+// the export omits inline credential-related fields.
-// secrets live in the SecretStore, not in profiles).
 func (s *Store) ExportProfiles(includeSecrets bool) ([]byte, error) {
 	profiles, err := s.ListProfiles()
 	if err != nil {
 		return nil, fmt.Errorf("storage: export failed: %w", err)
 	}
+	if !includeSecrets {
+		profiles = redactProfileSecrets(profiles)
+	}
 	return json.MarshalIndent(profiles, "", "  ")
 }
 
@@ -720,6 +722,21 @@ func nullableJSON(ptr interface{}, data []byte) interface{} {
 	return string(data)
 }
 
+func redactProfileSecrets(profiles []*models.Profile) []*models.Profile {
+	redacted := make([]*models.Profile, len(profiles))
+	for i, profile := range profiles {
+		cp := *profile
+		if cp.SSH != nil {
+			sshCfg := *cp.SSH
+			sshCfg.ProxyPassword = ""
+			sshCfg.TOTPSecret = ""
+			cp.SSH = &sshCfg
+		}
+		redacted[i] = &cp
+	}
+	return redacted
+}
+
 // ---------------------------------------------------------------------------
 // Snippet CRUD
 // ---------------------------------------------------------------------------

internal/vncclient/vncclient.go

@@ -4,6 +4,8 @@ package vncclient
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/hex"
 	"fmt"
 	"net"
 	"net/http"
@@ -44,6 +46,7 @@ type Config struct {
 	SSHPassphrase      string
 	SSHAgentAuth       bool
 	SSHAgentConn       net.Conn
+	SSHHostKeyCallback ssh.HostKeyCallback
 
 	// Callbacks
 	OnError func(error)
@@ -83,9 +86,12 @@ func (c *Client) Connect(cfg Config) (string, error) {
 	if cfg.SSHTunnel {
 		// Establish SSH connection first
 		sshAddr := fmt.Sprintf("%s:%d", cfg.SSHHost, cfg.SSHPort)
+		if cfg.SSHHostKeyCallback == nil {
+			return "", fmt.Errorf("SSH host key callback is required")
+		}
 		sshConfig := &ssh.ClientConfig{
 			User:            cfg.SSHUsername,
-			HostKeyCallback: ssh.InsecureIgnoreHostKey(), // TODO: use known hosts
+			HostKeyCallback: cfg.SSHHostKeyCallback,
 			Timeout:         15 * time.Second,
 		}
 
@@ -162,13 +168,19 @@ func (c *Client) startProxy(vncConn net.Conn) (string, error) {
 	if err != nil {
 		return "", err
 	}
+	token, err := newProxyToken()
+	if err != nil {
+		listener.Close()
+		return "", err
+	}
 	c.listener = listener
 
 	port := listener.Addr().(*net.TCPAddr).Port
-	wsURL := fmt.Sprintf("ws://127.0.0.1:%d", port)
+	proxyPath := "/" + token
+	wsURL := fmt.Sprintf("ws://127.0.0.1:%d%s", port, proxyPath)
 
 	mux := http.NewServeMux()
-	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+	mux.HandleFunc(proxyPath, func(w http.ResponseWriter, r *http.Request) {
 		ws, err := upgrader.Upgrade(w, r, nil)
 		if err != nil {
 			return
@@ -240,6 +252,14 @@ func (c *Client) startProxy(vncConn net.Conn) (string, error) {
 	return wsURL, nil
 }
 
+func newProxyToken() (string, error) {
+	token := make([]byte, 16)
+	if _, err := rand.Read(token); err != nil {
+		return "", fmt.Errorf("generate proxy token: %w", err)
+	}
+	return hex.EncodeToString(token), nil
+}
+
 // Close shuts down the VNC proxy and any SSH tunnel.
 func (c *Client) Close() {
 	c.mu.Lock()

internal/vncclient/vncclient_test.go

@@ -0,0 +1,26 @@
+package vncclient
+
+import "testing"
+
+func TestNewProxyTokenIsRandomHex(t *testing.T) {
+	first, err := newProxyToken()
+	if err != nil {
+		t.Fatalf("newProxyToken() error = %v", err)
+	}
+	second, err := newProxyToken()
+	if err != nil {
+		t.Fatalf("newProxyToken() second error = %v", err)
+	}
+
+	if len(first) != 32 {
+		t.Fatalf("token length = %d, want 32", len(first))
+	}
+	if first == second {
+		t.Fatal("expected separate tokens to differ")
+	}
+	for _, ch := range first {
+		if !((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'f')) {
+			t.Fatalf("token contains non-hex character %q", ch)
+		}
+	}
+}