Security Issues in GitHub Copilot Code

Copilot sometimes suggests patterns from its training data that are known to be insecure — eval(), innerHTML, deprecated crypto functions, and hardcoded placeholder credentials that look like real keys. It can also perpetuate existing security anti-patterns in your codebase

Run a static analysis security scan (Semgrep, ESLint security plugins). Review all Copilot-generated code touching authentication, data access, or user input. Replace any deprecated APIs with current equivalents. Remove any placeholder credentials and verify all secrets use environment variables

Every GitHub Copilot app needs authentication — verifying who the user is — and authorization — verifying what they're allowed to do. Check that every API route and server action verifies the user's identity before processing requests. Check that users can only access their own data. A common GitHub Copilot pattern is adding auth to the UI but not the API, which means anyone with the endpoint URL can access data directly.

Never trust data coming from the client. Every form submission, URL parameter, and API request body should be validated server-side before processing. Use a schema validation library like Zod to define expected shapes and reject anything that doesn't match. This prevents injection attacks, data corruption, and unexpected crashes.

Configure security headers to protect against common web attacks: Content-Security-Policy to prevent XSS, Strict-Transport-Security to enforce HTTPS, X-Frame-Options to prevent clickjacking, and X-Content-Type-Options to prevent MIME sniffing. Most hosting platforms let you configure these in a headers file or configuration.

If your app handles user data, processes payments, or stores sensitive information, a professional security review is essential before launch. Our security scan ($19) checks for the most critical vulnerabilities, and our full security review service provides a comprehensive assessment with remediation guidance.