fix: harden security resource lifecycles

build-all.sh

@@ -17,7 +17,7 @@ log()  { echo -e "${GREEN}[nexus]${NC} $1"; }
 warn() { echo -e "${YELLOW}[nexus]${NC} $1"; }
 err()  { echo -e "${RED}[nexus]${NC} $1" >&2; }
 
-MIN_GO_VERSION="1.25.0"
+MIN_GO_VERSION="1.25.12"
 WAILS_VERSION="$(awk '$1 == "github.com/wailsapp/wails/v2" { print $2; exit }' go.mod)"
 WAILS_BIN=""
 WAILS_USE_GO_RUN=0

build.sh

@@ -18,7 +18,7 @@ log()  { echo -e "${GREEN}[nexus]${NC} $1"; }
 warn() { echo -e "${YELLOW}[nexus]${NC} $1"; }
 err()  { echo -e "${RED}[nexus]${NC} $1" >&2; }
 
-MIN_GO_VERSION="1.25.0"
+MIN_GO_VERSION="1.25.12"
 WAILS_VERSION="$(nexus_wails_version go.mod)"
 WAILS_BIN=""
 WAILS_USE_GO_RUN=0

cmd/vscode-bridge/main.go

@@ -184,8 +184,11 @@ func newBridgeApp() (*bridgeApp, error) {
 }
 
 func (a *bridgeApp) close() {
+	if a.service != nil {
+		a.service.Shutdown()
+	}
 	if a.manager != nil {
-		a.manager.CloseAll()
+		a.manager.Shutdown()
 	}
 	if a.store != nil {
 		_ = a.store.Close()
@@ -243,7 +246,7 @@ func (a *bridgeApp) handleRuntimeEvent(w http.ResponseWriter, r *http.Request) {
 		value, _ := req.Payload["value"].(string)
 		cancelled, _ := req.Payload["cancelled"].(bool)
 		a.service.RespondSecret(requestID, value, cancelled)
-		a.manager.RespondSecret(requestID, value)
+		a.manager.RespondSecret(requestID, value, cancelled)
 	case "session:hostkey:response":
 		requestID, _ := req.Payload["requestID"].(string)
 		accepted, _ := req.Payload["accepted"].(bool)

frontend/scripts/test-regressions.js

@@ -315,21 +315,6 @@ assertContains(
   "VNC Connections",
   "in-app help must document VNC connection profiles",
 );
-assertContains(
-  "vscode/nexus/extension.js",
-  "crypto.randomBytes(16).toString('base64')",
-  "Nexus VS Code webview CSP nonces must use cryptographic randomness",
-);
-assertContains(
-  "vscode/leviathan/extension.js",
-  "crypto.randomBytes(16).toString('base64')",
-  "Leviathan VS Code webview CSP nonces must use cryptographic randomness",
-);
-assertTreeNotContains(
-  "vscode",
-  "const nonce = String(Date.now());",
-  "VS Code webview CSP nonces must not be predictable timestamps",
-);
 assertContains(
   "docs/user-manual.md",
   "## 11. Leviathan binary workbench",
@@ -558,8 +543,8 @@ assertContains(
 );
 assertContains(
   "scripts/build-common.sh",
-  "-O2 -g0",
-  "production builds must remove cgo debug output by default",
+  "CGO_ENABLED=0",
+  "production builds must keep the pure-Go SQLite toolchain",
 );
 assertContains(
   "Makefile",

go.mod

@@ -1,6 +1,8 @@
 module github.com/andydixon/nexus
 
-go 1.25.0
+go 1.25.12
+
+toolchain go1.26.5
 
 require (
 	github.com/creack/pty v1.1.24

internal/api/api.go

@@ -16,6 +16,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -48,6 +49,7 @@ const (
 	maxInlineSFTPUploadBytes   = 25 * 1024 * 1024
 	maxSFTPUploadChunkBytes    = 1024 * 1024
 	maxStreamingSFTPUploadSize = int64(2 * 1024 * 1024 * 1024)
+	maxConcurrentSFTPUploads   = 16
 	maxSSHPublicKeyBytes       = 64 * 1024
 	sshKeygenTimeout           = 30 * time.Second
 )
@@ -64,8 +66,10 @@ type Service struct {
 	eventSink     func(string, interface{})
 
 	// secretChans maps request IDs to channels awaiting user secret input.
-	secretMu    sync.Mutex
-	secretChans map[string]chan secretResponse
+	secretMu                 sync.Mutex
+	secretChans              map[string]chan secretResponse
+	secretListenerRegistered bool
+	secretListenerCancel     func()
 
 	uploadMu sync.Mutex
 	uploads  map[string]*sftpUpload
@@ -108,6 +112,30 @@ func (s *Service) SetContext(ctx context.Context) {
 	s.RegisterSecretResponseListener()
 }
 
+// Shutdown releases active uploads, prompt waiters, and app-wide Wails
+// listeners. It is safe to call when no Wails context was configured.
+func (s *Service) Shutdown() {
+	s.cancelSFTPUploads("")
+
+	s.secretMu.Lock()
+	cancel := s.secretListenerCancel
+	s.secretListenerCancel = nil
+	s.secretListenerRegistered = false
+	waiters := s.secretChans
+	s.secretChans = make(map[string]chan secretResponse)
+	s.secretMu.Unlock()
+
+	if cancel != nil {
+		cancel()
+	}
+	for _, ch := range waiters {
+		select {
+		case ch <- secretResponse{cancelled: true}:
+		default:
+		}
+	}
+}
+
 // SetEventSink registers an alternate UI event sink for non-Wails hosts such
 // as the VS Code bridge.
 func (s *Service) SetEventSink(sink func(string, interface{})) {
@@ -438,11 +466,13 @@ func (s *Service) RestartLocalSession(sessionID string, cols int, rows int) erro
 
 // DisconnectSession closes a session by ID.
 func (s *Service) DisconnectSession(sessionID string) error {
+	s.cancelSFTPUploads(sessionID)
 	return s.sessions.Disconnect(sessionID)
 }
 
 // ReconnectSession closes and re-establishes a session.
 func (s *Service) ReconnectSession(sessionID string) error {
+	s.cancelSFTPUploads(sessionID)
 	return s.sessions.Reconnect(sessionID, s.promptSecret)
 }
 
@@ -482,6 +512,7 @@ func (s *Service) PinSession(sessionID string, pinned bool) error {
 
 // CloseAllSessions terminates all active sessions.
 func (s *Service) CloseAllSessions() {
+	s.cancelSFTPUploads("")
 	s.sessions.CloseAll()
 }
 
@@ -1538,6 +1569,9 @@ func (s *Service) SFTPUploadStart(sessionID string, remoteDir string, fileName s
 	if totalBytes > maxStreamingSFTPUploadSize {
 		return "", fmt.Errorf("upload is too large (max %d bytes)", maxStreamingSFTPUploadSize)
 	}
+	if err := s.checkSFTPUploadCapacity(); err != nil {
+		return "", err
+	}
 
 	safeName, err := safeSFTPUploadName(fileName)
 	if err != nil {
@@ -1551,6 +1585,14 @@ func (s *Service) SFTPUploadStart(sessionID string, remoteDir string, fileName s
 
 	uploadID := uuid.New().String()
 	s.uploadMu.Lock()
+	if len(s.uploads) >= maxConcurrentSFTPUploads {
+		s.uploadMu.Unlock()
+		_ = writer.Close()
+		if s.sessions != nil {
+			_ = s.sessions.SFTPRemove(sessionID, remotePath)
+		}
+		return "", fmt.Errorf("too many active uploads (max %d)", maxConcurrentSFTPUploads)
+	}
 	s.uploads[uploadID] = &sftpUpload{
 		writer:     writer,
 		sessionID:  sessionID,
@@ -1716,7 +1758,7 @@ func (s *Service) TestConnection(host string, port int) (map[string]interface{},
 		return nil, fmt.Errorf("port must be between 1 and 65535")
 	}
 
-	addr := fmt.Sprintf("%s:%d", host, port)
+	addr := net.JoinHostPort(host, strconv.Itoa(port))
 	start := time.Now()
 
 	conn, err := net.DialTimeout("tcp", addr, 10*time.Second)
@@ -1798,7 +1840,16 @@ func (s *Service) RegisterSecretResponseListener() {
 	if s.ctx == nil {
 		return
 	}
-	wailsRuntime.EventsOn(s.ctx, "session:secret:response", func(optionalData ...interface{}) {
+
+	s.secretMu.Lock()
+	if s.secretListenerRegistered {
+		s.secretMu.Unlock()
+		return
+	}
+	s.secretListenerRegistered = true
+	s.secretMu.Unlock()
+
+	cancel := wailsRuntime.EventsOn(s.ctx, "session:secret:response", func(optionalData ...interface{}) {
 		if len(optionalData) == 0 {
 			return
 		}
@@ -1815,9 +1866,15 @@ func (s *Service) RegisterSecretResponseListener() {
 		s.secretMu.Unlock()
 
 		if exists {
-			ch <- secretResponse{value: value, cancelled: cancelled}
+			select {
+			case ch <- secretResponse{value: value, cancelled: cancelled}:
+			default:
+			}
 		}
 	})
+	s.secretMu.Lock()
+	s.secretListenerCancel = cancel
+	s.secretMu.Unlock()
 }
 
 // RespondSecret supplies a credential prompt response for non-Wails hosts.
@@ -1827,7 +1884,10 @@ func (s *Service) RespondSecret(requestID string, value string, cancelled bool)
 	s.secretMu.Unlock()
 
 	if exists {
-		ch <- secretResponse{value: value, cancelled: cancelled}
+		select {
+		case ch <- secretResponse{value: value, cancelled: cancelled}:
+		default:
+		}
 	}
 }
 
@@ -2127,6 +2187,39 @@ func (s *Service) removeSFTPUpload(uploadID string) {
 	delete(s.uploads, uploadID)
 }
 
+func (s *Service) checkSFTPUploadCapacity() error {
+	s.uploadMu.Lock()
+	defer s.uploadMu.Unlock()
+	if len(s.uploads) >= maxConcurrentSFTPUploads {
+		return fmt.Errorf("too many active uploads (max %d)", maxConcurrentSFTPUploads)
+	}
+	return nil
+}
+
+// cancelSFTPUploads closes and removes active uploads. An empty session ID
+// cancels every upload; otherwise only uploads owned by that session are
+// affected.
+func (s *Service) cancelSFTPUploads(sessionID string) {
+	s.uploadMu.Lock()
+	uploads := make([]*sftpUpload, 0)
+	for uploadID, upload := range s.uploads {
+		if sessionID == "" || upload.sessionID == sessionID {
+			delete(s.uploads, uploadID)
+			uploads = append(uploads, upload)
+		}
+	}
+	s.uploadMu.Unlock()
+
+	for _, upload := range uploads {
+		upload.mu.Lock()
+		_ = upload.writer.Close()
+		upload.mu.Unlock()
+		if s.sessions != nil {
+			_ = s.sessions.SFTPRemove(upload.sessionID, upload.remotePath)
+		}
+	}
+}
+
 func validateImportStrategy(strategy string) error {
 	switch strategy {
 	case "skip", "overwrite", "duplicate":

internal/api/api_test.go

@@ -13,6 +13,19 @@ import (
 	"github.com/andydixon/nexus/internal/storage"
 )
 
+type closeTrackingWriter struct {
+	closed int
+}
+
+func (w *closeTrackingWriter) Write(p []byte) (int, error) {
+	return len(p), nil
+}
+
+func (w *closeTrackingWriter) Close() error {
+	w.closed++
+	return nil
+}
+
 func TestSSHKeyPairPathsAcceptsSafeName(t *testing.T) {
 	home := t.TempDir()
 	t.Setenv("HOME", home)
@@ -128,6 +141,65 @@ func TestSFTPUploadChunkRejectsOversizedChunkBeforeUploadLookup(t *testing.T) {
 	}
 }
 
+func TestCancelSFTPUploadsClosesOnlyMatchingSession(t *testing.T) {
+	first := &closeTrackingWriter{}
+	second := &closeTrackingWriter{}
+	svc := &Service{
+		uploads: map[string]*sftpUpload{
+			"first":  {writer: first, sessionID: "session-1", remotePath: "/first"},
+			"second": {writer: second, sessionID: "session-2", remotePath: "/second"},
+		},
+	}
+
+	svc.cancelSFTPUploads("session-1")
+
+	if first.closed != 1 {
+		t.Fatalf("matching writer closed %d times, want 1", first.closed)
+	}
+	if second.closed != 0 {
+		t.Fatalf("unrelated writer closed %d times, want 0", second.closed)
+	}
+	if len(svc.uploads) != 1 || svc.uploads["second"] == nil {
+		t.Fatalf("remaining uploads = %#v, want only session-2", svc.uploads)
+	}
+}
+
+func TestSFTPUploadCapacityIsBounded(t *testing.T) {
+	svc := &Service{uploads: make(map[string]*sftpUpload)}
+	for i := 0; i < maxConcurrentSFTPUploads; i++ {
+		svc.uploads[string(rune('a'+i))] = &sftpUpload{writer: &closeTrackingWriter{}}
+	}
+	if err := svc.checkSFTPUploadCapacity(); err == nil {
+		t.Fatal("expected active upload limit to be enforced")
+	}
+}
+
+func TestServiceShutdownReleasesUploadsAndSecretWaiters(t *testing.T) {
+	writer := &closeTrackingWriter{}
+	waiter := make(chan secretResponse, 1)
+	svc := &Service{
+		uploads:     map[string]*sftpUpload{"upload": {writer: writer}},
+		secretChans: map[string]chan secretResponse{"prompt": waiter},
+	}
+
+	svc.Shutdown()
+
+	if writer.closed != 1 {
+		t.Fatalf("writer closed %d times, want 1", writer.closed)
+	}
+	if len(svc.uploads) != 0 {
+		t.Fatalf("active uploads = %d, want 0", len(svc.uploads))
+	}
+	select {
+	case response := <-waiter:
+		if !response.cancelled {
+			t.Fatal("shutdown response was not cancelled")
+		}
+	default:
+		t.Fatal("shutdown did not release secret prompt waiter")
+	}
+}
+
 func TestSafeSFTPUploadNamePreservesHTMLCharacters(t *testing.T) {
 	got, err := safeSFTPUploadName(`../report <final>.txt`)
 	if err != nil {

internal/app/app.go

@@ -118,8 +118,12 @@ func (a *App) Shutdown(ctx context.Context) {
 	a.mu.Lock()
 	defer a.mu.Unlock()
 
+	if a.Service != nil {
+		a.Service.Shutdown()
+	}
+
 	if a.SessionManager != nil {
-		a.SessionManager.CloseAll()
+		a.SessionManager.Shutdown()
 	}
 
 	if a.Store != nil {

internal/exportimport/exportimport.go

@@ -68,6 +68,7 @@ func EncryptAndExport(profiles []models.Profile, password, filePath string) erro
 	if err != nil {
 		return fmt.Errorf("exportimport: failed to serialise profiles: %w", err)
 	}
+	defer clear(plaintext)
 
 	// Generate random salt and nonce.
 	salt := make([]byte, saltLength)
@@ -81,14 +82,17 @@ func EncryptAndExport(profiles []models.Profile, password, filePath string) erro
 	}
 
 	// Derive encryption key from password.
+	passwordBytes := []byte(password)
+	defer clear(passwordBytes)
 	key := argon2.IDKey(
-		[]byte(password),
+		passwordBytes,
 		salt,
 		exportArgonTime,
 		exportArgonMemory,
 		exportArgonThreads,
 		exportArgonKeyLen,
 	)
+	defer clear(key)
 
 	// Encrypt with AES-256-GCM.
 	block, err := aes.NewCipher(key)
@@ -104,11 +108,14 @@ func EncryptAndExport(profiles []models.Profile, password, filePath string) erro
 	ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
 
 	// Write the file: version + salt + nonce + ciphertext.
-	f, err := os.Create(filePath)
+	f, err := os.OpenFile(filePath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0600)
 	if err != nil {
 		return fmt.Errorf("exportimport: failed to create file: %w", err)
 	}
 	defer f.Close()
+	if err := f.Chmod(0600); err != nil {
+		return fmt.Errorf("exportimport: failed to restrict file permissions: %w", err)
+	}
 
 	if _, err := f.Write([]byte{formatVersion}); err != nil {
 		return fmt.Errorf("exportimport: write version failed: %w", err)
@@ -163,14 +170,17 @@ func DecryptAndImport(filePath, password string) ([]models.Profile, error) {
 	ciphertext := data[1+saltLength+nonceLength:]
 
 	// Derive decryption key.
+	passwordBytes := []byte(password)
+	defer clear(passwordBytes)
 	key := argon2.IDKey(
-		[]byte(password),
+		passwordBytes,
 		salt,
 		exportArgonTime,
 		exportArgonMemory,
 		exportArgonThreads,
 		exportArgonKeyLen,
 	)
+	defer clear(key)
 
 	// Decrypt with AES-256-GCM.
 	block, err := aes.NewCipher(key)
@@ -187,6 +197,7 @@ func DecryptAndImport(filePath, password string) ([]models.Profile, error) {
 	if err != nil {
 		return nil, errors.New("exportimport: decryption failed — wrong password or corrupt file")
 	}
+	defer clear(plaintext)
 
 	// Parse the JSON bundle.
 	var bundle ExportBundle

internal/exportimport/exportimport_test.go

@@ -3,6 +3,7 @@ package exportimport
 import (
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 
 	"github.com/andydixon/nexus/internal/models"
@@ -104,6 +105,26 @@ func TestEncryptEmptyProfiles(t *testing.T) {
 	}
 }
 
+func TestEncryptAndExportRestrictsExistingFilePermissions(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("POSIX permission bits are not enforced on Windows")
+	}
+	path := filepath.Join(t.TempDir(), "profiles.nexus")
+	if err := os.WriteFile(path, []byte("old"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := EncryptAndExport([]models.Profile{{ID: "1"}}, "password", path); err != nil {
+		t.Fatal(err)
+	}
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := info.Mode().Perm(); got != 0600 {
+		t.Fatalf("export permissions = %04o, want 0600", got)
+	}
+}
+
 func TestEncryptEmptyPassword(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "test.nexus")

internal/ircclient/ircclient.go

@@ -608,7 +608,7 @@ func (c *Client) newSSHDialer() (*sshDialer, error) {
 	if err != nil {
 		return nil, err
 	}
-	sshAddr := fmt.Sprintf("%s:%d", c.cfg.SSHHost, c.cfg.SSHPort)
+	sshAddr := net.JoinHostPort(c.cfg.SSHHost, strconv.Itoa(c.cfg.SSHPort))
 	sshConfig := &ssh.ClientConfig{
 		User:            c.cfg.SSHUsername,
 		Auth:            authMethods,

internal/leviathan/binsnoop/binsnoop.go

@@ -134,11 +134,11 @@ func CarveResult(data []byte, result SignatureResult, outputDir string) error {
 	if result.Offset < 0 || result.Offset+result.Size > len(data) {
 		return fmt.Errorf("binsnoop: result offset/size exceeds data bounds")
 	}
-	if err := os.MkdirAll(outputDir, 0755); err != nil {
+	if err := os.MkdirAll(outputDir, 0700); err != nil {
 		return fmt.Errorf("binsnoop: mkdir: %w", err)
 	}
 	outPath := filepath.Join(outputDir, fmt.Sprintf("%x_%s.bin", result.Offset, result.Name))
-	return os.WriteFile(outPath, data[result.Offset:result.Offset+result.Size], 0644)
+	return os.WriteFile(outPath, data[result.Offset:result.Offset+result.Size], 0600)
 }
 
 // SignatureCount returns the number of loaded signatures.

internal/leviathan/binsnoop/common_test.go

@@ -3,6 +3,7 @@ package binsnoop
 import (
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -20,3 +21,27 @@ func TestReadFileLimitedRejectsOversizedFile(t *testing.T) {
 		t.Fatalf("unexpected error: %v", err)
 	}
 }
+
+func TestCarveUsesPrivatePermissions(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("POSIX permission bits are not enforced on Windows")
+	}
+	path := filepath.Join(t.TempDir(), "private", "carved.bin")
+	if err := Carve(path, []byte("secret"), 0, 6); err != nil {
+		t.Fatal(err)
+	}
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := info.Mode().Perm(); got != 0600 {
+		t.Fatalf("carved file permissions = %04o, want 0600", got)
+	}
+	dirInfo, err := os.Stat(filepath.Dir(path))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := dirInfo.Mode().Perm(); got != 0700 {
+		t.Fatalf("carve directory permissions = %04o, want 0700", got)
+	}
+}

internal/leviathan/binsnoop/extract.go

@@ -14,10 +14,10 @@ func Carve(outputPath string, data []byte, offset, size int) error {
 		return fmt.Errorf("carve: offset %d + size %d exceeds data length %d", offset, size, len(data))
 	}
 	dir := filepath.Dir(outputPath)
-	if err := os.MkdirAll(dir, 0755); err != nil {
+	if err := os.MkdirAll(dir, 0700); err != nil {
 		return fmt.Errorf("carve: mkdir: %w", err)
 	}
-	return os.WriteFile(outputPath, data[offset:offset+size], 0644)
+	return os.WriteFile(outputPath, data[offset:offset+size], 0600)
 }
 
 // executeExternal runs an external extraction tool.
@@ -27,7 +27,7 @@ func executeExternal(ext *Extractor, carvedFilePath, outputDir string) *Extracti
 		OutputDirectory: outputDir,
 	}
 
-	if err := os.MkdirAll(outputDir, 0755); err != nil {
+	if err := os.MkdirAll(outputDir, 0700); err != nil {
 		return result
 	}
 
@@ -100,7 +100,7 @@ func ExecuteExtraction(data []byte, filePath string, sig *SignatureResult, ext *
 
 	case ExtractorTypeExternal:
 		// Carve data to a temp file for external tools
-		if err := os.MkdirAll(outputDir, 0755); err != nil {
+		if err := os.MkdirAll(outputDir, 0700); err != nil {
 			return &ExtractionResult{OutputDirectory: outputDir}
 		}
 
@@ -109,7 +109,7 @@ func ExecuteExtraction(data []byte, filePath string, sig *SignatureResult, ext *
 		if endOffset > len(data) {
 			endOffset = len(data)
 		}
-		if err := os.WriteFile(carvedFile, data[sig.Offset:endOffset], 0644); err != nil {
+		if err := os.WriteFile(carvedFile, data[sig.Offset:endOffset], 0600); err != nil {
 			return &ExtractionResult{OutputDirectory: outputDir}
 		}
 

internal/sessions/manager.go

@@ -82,8 +82,16 @@ type Manager struct {
 	hostKeyMu                 sync.Mutex
 	hostKeyChans              map[string]chan bool
 	hostKeyListenerRegistered bool
+	hostKeyListenerCancel     func()
 	secretMu                  sync.Mutex
-	secretChans               map[string]chan string
+	secretChans               map[string]chan secretPromptResponse
+	secretListenerRegistered  bool
+	secretListenerCancel      func()
+}
+
+type secretPromptResponse struct {
+	value     string
+	cancelled bool
 }
 
 // NewManager creates a Manager wired to the given backing services.
@@ -102,6 +110,7 @@ func NewManager(store *storage.Store, secretStore *secrets.SecretStore, keychain
 func (m *Manager) SetContext(ctx context.Context) {
 	m.ctx = ctx
 	m.registerHostKeyResponseListener()
+	m.registerSecretResponseListener()
 }
 
 // SetEventSink registers an alternate UI event sink for non-Wails hosts.
@@ -662,6 +671,46 @@ func (m *Manager) CloseAll() {
 	}
 }
 
+// Shutdown closes all sessions, unregisters app-wide Wails listeners, and
+// releases any prompts still waiting for frontend input.
+func (m *Manager) Shutdown() {
+	m.CloseAll()
+
+	m.hostKeyMu.Lock()
+	hostKeyCancel := m.hostKeyListenerCancel
+	m.hostKeyListenerCancel = nil
+	m.hostKeyListenerRegistered = false
+	hostKeyChans := m.hostKeyChans
+	m.hostKeyChans = make(map[string]chan bool)
+	m.hostKeyMu.Unlock()
+	if hostKeyCancel != nil {
+		hostKeyCancel()
+	}
+	for _, ch := range hostKeyChans {
+		select {
+		case ch <- false:
+		default:
+		}
+	}
+
+	m.secretMu.Lock()
+	secretCancel := m.secretListenerCancel
+	m.secretListenerCancel = nil
+	m.secretListenerRegistered = false
+	secretChans := m.secretChans
+	m.secretChans = make(map[string]chan secretPromptResponse)
+	m.secretMu.Unlock()
+	if secretCancel != nil {
+		secretCancel()
+	}
+	for _, ch := range secretChans {
+		select {
+		case ch <- secretPromptResponse{cancelled: true}:
+		default:
+		}
+	}
+}
+
 // GetSessionHistory returns the RAW session history (RAW protocol only).
 func (m *Manager) GetSessionHistory(sessionID string) ([]rawclient.HistoryEntry, error) {
 	m.mu.RLock()
@@ -1990,7 +2039,10 @@ func (m *Manager) registerHostKeyResponseListener() {
 	m.hostKeyListenerRegistered = true
 	m.hostKeyMu.Unlock()
 
-	wailsRuntime.EventsOn(ctx, "session:hostkey:response", m.handleHostKeyResponse)
+	cancel := wailsRuntime.EventsOn(ctx, "session:hostkey:response", m.handleHostKeyResponse)
+	m.hostKeyMu.Lock()
+	m.hostKeyListenerCancel = cancel
+	m.hostKeyMu.Unlock()
 }
 
 func (m *Manager) handleHostKeyResponse(optionalData ...interface{}) {
@@ -2467,13 +2519,13 @@ func (m *Manager) scheduleReconnect(sess *Session, sessionID string) {
 		var err error
 		switch sess.profile.Protocol {
 		case models.ProtocolSSH:
-			err = m.connectSSH(sess, m.buildInteractiveSecretCallback(sessionID))
+			err = m.connectSSH(sess, m.buildInteractiveSecretCallback(ctx, sessionID))
 		case models.ProtocolTelnet:
 			err = m.connectTelnet(sess)
 		case models.ProtocolRAW:
 			err = m.connectRAW(sess)
 		case models.ProtocolIRC:
-			err = m.connectIRC(sess, m.buildInteractiveSecretCallback(sessionID))
+			err = m.connectIRC(sess, m.buildInteractiveSecretCallback(ctx, sessionID))
 		default:
 			err = fmt.Errorf("unsupported protocol for reconnect: %s", sess.profile.Protocol)
 		}
@@ -2522,14 +2574,14 @@ func (m *Manager) scheduleReconnect(sess *Session, sessionID string) {
 // buildInteractiveSecretCallback creates a getSecret callback that prompts
 // the user via Wails events. Used during auto-reconnect flows where the
 // original callback is no longer available.
-func (m *Manager) buildInteractiveSecretCallback(sessionID string) func(prompt string) (string, error) {
+func (m *Manager) buildInteractiveSecretCallback(ctx context.Context, sessionID string) func(prompt string) (string, error) {
 	return func(prompt string) (string, error) {
 		requestID := uuid.New().String()
 
-		ch := make(chan string, 1)
+		ch := make(chan secretPromptResponse, 1)
 		m.secretMu.Lock()
 		if m.secretChans == nil {
-			m.secretChans = make(map[string]chan string)
+			m.secretChans = make(map[string]chan secretPromptResponse)
 		}
 		m.secretChans[requestID] = ch
 		m.secretMu.Unlock()
@@ -2546,48 +2598,67 @@ func (m *Manager) buildInteractiveSecretCallback(sessionID string) func(prompt s
 			"message":   prompt,
 		})
 
-		// Wait for the response with a timeout.
-		var response string
-
-		if m.ctx != nil {
-			wailsRuntime.EventsOn(m.ctx, "session:secret:response", func(optionalData ...interface{}) {
-				if len(optionalData) == 0 {
-					return
-				}
-				data, ok := optionalData[0].(map[string]interface{})
-				if !ok {
-					return
-				}
-				if rid, _ := data["requestID"].(string); rid == requestID {
-					val, _ := data["value"].(string)
-					select {
-					case ch <- val:
-					default:
-					}
-				}
-			})
-		}
-
 		select {
-		case response = <-ch:
+		case response := <-ch:
+			if response.cancelled {
+				return "", fmt.Errorf("credential prompt cancelled during reconnect")
+			}
+			return response.value, nil
+		case <-ctx.Done():
+			return "", fmt.Errorf("credential prompt cancelled during reconnect: %w", ctx.Err())
 		case <-time.After(60 * time.Second):
 			return "", fmt.Errorf("credential prompt timed out during reconnect")
 		}
-
-		return response, nil
 	}
 }
 
+func (m *Manager) registerSecretResponseListener() {
+	ctx := m.ctx
+	if ctx == nil {
+		return
+	}
+
+	m.secretMu.Lock()
+	if m.secretChans == nil {
+		m.secretChans = make(map[string]chan secretPromptResponse)
+	}
+	if m.secretListenerRegistered {
+		m.secretMu.Unlock()
+		return
+	}
+	m.secretListenerRegistered = true
+	m.secretMu.Unlock()
+
+	cancel := wailsRuntime.EventsOn(ctx, "session:secret:response", m.handleSecretResponse)
+	m.secretMu.Lock()
+	m.secretListenerCancel = cancel
+	m.secretMu.Unlock()
+}
+
+func (m *Manager) handleSecretResponse(optionalData ...interface{}) {
+	if len(optionalData) == 0 {
+		return
+	}
+	data, ok := optionalData[0].(map[string]interface{})
+	if !ok {
+		return
+	}
+	requestID, _ := data["requestID"].(string)
+	value, _ := data["value"].(string)
+	cancelled, _ := data["cancelled"].(bool)
+	m.RespondSecret(requestID, value, cancelled)
+}
+
 // RespondSecret supplies a credential prompt response for reconnect prompts in
 // non-Wails hosts.
-func (m *Manager) RespondSecret(requestID string, value string) {
+func (m *Manager) RespondSecret(requestID string, value string, cancelled bool) {
 	m.secretMu.Lock()
 	ch, exists := m.secretChans[requestID]
 	m.secretMu.Unlock()
 
 	if exists {
 		select {
-		case ch <- value:
+		case ch <- secretPromptResponse{value: value, cancelled: cancelled}:
 		default:
 		}
 	}

internal/sessions/manager_test.go

@@ -1,6 +1,7 @@
 package sessions
 
 import (
+	"context"
 	"crypto/ed25519"
 	"crypto/rand"
 	"encoding/base64"
@@ -377,6 +378,101 @@ func TestHandleHostKeyResponseIgnoresOtherRequestIDs(t *testing.T) {
 	}
 }
 
+func TestHandleSecretResponseRoutesByRequestID(t *testing.T) {
+	mgr := NewManager(nil, nil, nil, nil, nil)
+	ch := make(chan secretPromptResponse, 1)
+	mgr.secretChans = map[string]chan secretPromptResponse{"request-1": ch}
+
+	mgr.handleSecretResponse(map[string]interface{}{
+		"requestID": "request-1",
+		"value":     "secret",
+		"cancelled": false,
+	})
+
+	select {
+	case response := <-ch:
+		if response.value != "secret" || response.cancelled {
+			t.Fatalf("response = %#v, want non-cancelled secret", response)
+		}
+	default:
+		t.Fatal("expected secret response to be routed")
+	}
+}
+
+func TestInteractiveSecretPromptIsReleasedByReconnectCancellation(t *testing.T) {
+	mgr := NewManager(nil, nil, nil, nil, nil)
+	prompts := make(chan map[string]interface{}, 1)
+	mgr.SetEventSink(func(name string, data interface{}) {
+		if name == "session:secret:prompt" {
+			prompts <- data.(map[string]interface{})
+		}
+	})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	result := make(chan error, 1)
+	go func() {
+		_, err := mgr.buildInteractiveSecretCallback(ctx, "session-1")("Password")
+		result <- err
+	}()
+
+	select {
+	case <-prompts:
+	case <-time.After(time.Second):
+		t.Fatal("timed out waiting for secret prompt")
+	}
+	cancel()
+
+	select {
+	case err := <-result:
+		if err == nil || !strings.Contains(err.Error(), "cancelled") {
+			t.Fatalf("callback error = %v, want cancellation", err)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("secret prompt did not stop after reconnect cancellation")
+	}
+
+	mgr.secretMu.Lock()
+	pending := len(mgr.secretChans)
+	mgr.secretMu.Unlock()
+	if pending != 0 {
+		t.Fatalf("pending secret prompts = %d, want 0", pending)
+	}
+}
+
+func TestInteractiveSecretPromptHonoursFrontendCancellation(t *testing.T) {
+	mgr := NewManager(nil, nil, nil, nil, nil)
+	prompts := make(chan map[string]interface{}, 1)
+	mgr.SetEventSink(func(name string, data interface{}) {
+		if name == "session:secret:prompt" {
+			prompts <- data.(map[string]interface{})
+		}
+	})
+
+	result := make(chan error, 1)
+	go func() {
+		_, err := mgr.buildInteractiveSecretCallback(context.Background(), "session-1")("Password")
+		result <- err
+	}()
+
+	var requestID string
+	select {
+	case prompt := <-prompts:
+		requestID, _ = prompt["requestID"].(string)
+	case <-time.After(time.Second):
+		t.Fatal("timed out waiting for secret prompt")
+	}
+	mgr.RespondSecret(requestID, "", true)
+
+	select {
+	case err := <-result:
+		if err == nil || !strings.Contains(err.Error(), "cancelled") {
+			t.Fatalf("callback error = %v, want frontend cancellation", err)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("secret prompt did not stop after frontend cancellation")
+	}
+}
+
 func testPublicKey(t *testing.T) ssh.PublicKey {
 	t.Helper()
 	pub, _, err := ed25519.GenerateKey(rand.Reader)

internal/vncclient/vncclient.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -85,11 +86,11 @@ func (c *Client) Connect(cfg Config) (string, error) {
 	var vncConn net.Conn
 	var err error
 
-	vncAddr := fmt.Sprintf("%s:%d", cfg.VNCHost, cfg.VNCPort)
+	vncAddr := net.JoinHostPort(cfg.VNCHost, strconv.Itoa(cfg.VNCPort))
 
 	if cfg.SSHTunnel {
 		// Establish SSH connection first
-		sshAddr := fmt.Sprintf("%s:%d", cfg.SSHHost, cfg.SSHPort)
+		sshAddr := net.JoinHostPort(cfg.SSHHost, strconv.Itoa(cfg.SSHPort))
 		if cfg.SSHHostKeyCallback == nil {
 			return "", fmt.Errorf("SSH host key callback is required")
 		}