diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8b41c9e..f57c86f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,6 +22,8 @@ jobs:
                 working-directory: rust
         steps:
             - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+              with:
+                  persist-credentials: false
             - name: Linux dependencies (GUI libs, and sshd for the SSH integration tests)
               if: runner.os == 'Linux'
               run: |
@@ -39,6 +41,10 @@ jobs:
                 working-directory: rust
         steps:
             - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
-            - run: cargo install cargo-audit --locked
-            # Ignored advisories and their reasons live in rust/.cargo/audit.toml.
-            - run: cargo audit
+              with:
+                  persist-credentials: false
+            - run: cargo install cargo-audit --version 0.22.2 --locked
+            # Ignored advisories and their reasons live in rust/.cargo/audit.toml. Yanked crates
+            # fail the build; the fuzz workspace has its own lockfile, so it's audited too.
+            - run: cargo audit --deny yanked
+            - run: cargo audit --deny yanked --file fuzz/Cargo.lock
diff --git a/.github/workflows/fuzz.yml b/.github/workflows/fuzz.yml
index 678f4e6..a8d6b0f 100644
--- a/.github/workflows/fuzz.yml
+++ b/.github/workflows/fuzz.yml
@@ -21,10 +21,12 @@ jobs:
                 working-directory: rust/fuzz
         steps:
             - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+              with:
+                  persist-credentials: false
             - run: sudo apt-get update && sudo apt-get install -y libasound2-dev
             - run: rustup toolchain install nightly --profile minimal
             - run: cargo +nightly install cargo-fuzz --locked
-            - run: cargo +nightly fuzz run ${{ matrix.target }} -- -max_total_time=120 -rss_limit_mb=2048
+            - run: cargo +nightly fuzz run ${{ matrix.target }} -- -max_total_time=120 -rss_limit_mb=2048 -timeout=10
             - name: Upload crashing inputs
               if: failure()
               uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
diff --git a/.github/workflows/release-builds.yml b/.github/workflows/release-builds.yml
index 89a8a72..5fd29a2 100644
--- a/.github/workflows/release-builds.yml
+++ b/.github/workflows/release-builds.yml
@@ -6,8 +6,10 @@ on:
             - "v*"
     workflow_dispatch:
 
+# Building and testing runs every dependency's build scripts and tests, so those jobs only get a
+# read token. Publishing is a separate job that never runs project or dependency code.
 permissions:
-    contents: write
+    contents: read
 
 jobs:
     build:
@@ -31,6 +33,7 @@ jobs:
             - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
               with:
                   fetch-depth: 0
+                  persist-credentials: false
 
             - name: Rust toolchain (pinned by rust-toolchain.toml)
               run: rustup show active-toolchain || rustup toolchain install
@@ -59,8 +62,26 @@ jobs:
                       build/releases/manifest-*.json
                       build/releases/version-*.txt
 
-            - name: Attach to GitHub Release
-              if: startsWith(github.ref, 'refs/tags/')
-              uses: softprops/action-gh-release@3bb12739c298aeb8a4eeaf626c5b8d85266b0e65 # v2.6.2
+    publish:
+        name: Attach to GitHub Release
+        needs: build
+        if: startsWith(github.ref, 'refs/tags/')
+        runs-on: ubuntu-22.04
+        permissions:
+            contents: write
+        steps:
+            - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
               with:
-                  files: build/releases/*/NexusTerminal-*.zip
+                  path: artefacts
+            - name: Checksums
+              run: |
+                  find artefacts -name 'NexusTerminal-*.zip' | while read -r f; do
+                      (cd "$(dirname "$f")" && sha256sum "$(basename "$f")")
+                  done > SHA256SUMS
+                  cat SHA256SUMS
+            - uses: softprops/action-gh-release@3bb12739c298aeb8a4eeaf626c5b8d85266b0e65 # v2.6.2
+              with:
+                  files: |
+                      artefacts/*/*/NexusTerminal-*.zip
+                      artefacts/*/NexusTerminal-*.zip
+                      SHA256SUMS
diff --git a/updates/index.php b/updates/index.php
index 87f337d..33f7cb5 100644
--- a/updates/index.php
+++ b/updates/index.php
@@ -1,6 +1,8 @@
 <?php
-$platform = isset($_GET['platform']) ? $_GET['platform'] : '';
-$arch = isset($_GET['arch']) ? $_GET['arch'] : '';
+// Query parameters may arrive as arrays (?arch[]=x); treat anything but a string as absent.
+$param = function ($name) { return isset($_GET[$name]) && is_string($_GET[$name]) ? $_GET[$name] : ''; };
+$platform = $param('platform');
+$arch = $param('arch');
 $platform = preg_replace('/[^a-z0-9_-]/i', '', $platform);
 $arch = preg_replace('/[^a-z0-9_-]/i', '', $arch);
 
@@ -13,7 +15,8 @@ if ($platform && $arch) {
 }
 
 $accept = isset($_SERVER['HTTP_ACCEPT']) ? $_SERVER['HTTP_ACCEPT'] : '';
-$format = isset($_GET['format']) ? strtolower($_GET['format']) : '';
+$format = strtolower($param('format'));
+header('X-Content-Type-Options: nosniff');
 
 $wantsJson = $format === 'json' || strpos($accept, 'application/json') !== false;
 $wantsVersion = $format === 'version';