File Upload Extension and MIME Type Verification
Agents validate only the client-reported file extension (.jpg) without verifying magic bytes or blocking executable extensions (.svg, .html, .exe).
Review my codebase for "File Upload Extension and MIME Type Verification" (INJ-007). Issue: Agents validate only the client-reported file extension (.jpg) without verifying magic bytes or blocking executable extensions (.svg, .html, .exe). Remediation required: Validate file headers on the server and store uploaded assets in an isolated bucket with Content-Disposition: attachment. Please: 1. Locate any occurrences of this issue across my repository. 2. Refactor the code to follow production standards without breaking existing functionality. 3. Provide a clear command or step to test and verify the fix.
Why AI Assistants Write This Bug
Agents validate only the client-reported file extension (.jpg) without verifying magic bytes or blocking executable extensions (.svg, .html, .exe).
AI code generation prioritizes immediate syntax execution over production edge cases. When an assistant hits an undefined variable or strict type error, it frequently takes the path of least resistance rather than implementing standard pre-launch security patterns.
Code Comparison
// Vulnerable AI-generated pattern for: File Upload Extension and MIME Type Verification
// Problematic pattern: Agents validate only the client-reported file extension (.jpg) without verifying magic bytes or blocking executable extensions (.svg, .html, .exe).// Production-ready fix for: File Upload Extension and MIME Type Verification
// Recommended remediation: Validate file headers on the server and store uploaded assets in an isolated bucket with Content-Disposition: attachment.Remediation & Verification Checklist
- Search your codebase for pattern matching "File Upload Extension and MIME Type Verification".
- Apply the recommended remediation: Validate file headers on the server and store uploaded assets in an isolated bucket with Content-Disposition: attachment.
- Run local build and test commands to ensure no regressions.
- Verify in your browser or with curl that the issue is resolved.
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