validate alert id

Author: chargome

.github/workflows/fix-security-vulnerability.yml

@@ -32,7 +32,13 @@ jobs:
         id: alert
         run: |
           INPUT="${{ github.event.inputs.alert }}"
-          echo "number=${INPUT##*/}" >> "$GITHUB_OUTPUT"
+          RAW="${INPUT##*/}"
+          NUMBER="${RAW%%\?*}"
+          if ! [[ "$NUMBER" =~ ^[0-9]+$ ]]; then
+            echo "Error: Could not extract a valid numeric alert ID from input: $INPUT"
+            exit 1
+          fi
+          echo "number=$NUMBER" >> "$GITHUB_OUTPUT"
 
       - uses: anthropics/claude-code-action@v1
         with: