Security Review Checklist

Authentication & Authorization

• Passwords hashed with bcrypt/argon2 (NEVER md5/sha1/plain)
• JWT tokens have expiry (access: 15min, refresh: 7d)
• JWT secret is long (32+ chars), loaded from env var
• Refresh token rotation implemented (old token invalidated on use)
• Rate limiting on login (max 5 attempts, then lockout/slowdown)
• CSRF protection on state-changing endpoints (cookies)
• Auth check on EVERY protected route (not just the frontend)
• Admin endpoints have separate, stricter auth check

Input Validation

• ALL user input validated server-side (never trust client)
• File uploads: check MIME type, extension, size limit, scan for malware
• URL parameters parsed and validated (no direct string concat in SQL)
• JSON bodies have max size limit (e.g., 1MB)
• HTML/Markdown user content sanitized before rendering (XSS)

SQL & Data

• ALL queries use parameterized statements (no f-string SQL)
• ORM used for CRUD — raw SQL only for complex analytics
• Database user has minimum required permissions (not superuser)
• Sensitive fields (password, SSN, CC) never returned in API responses
• PII encrypted at rest for sensitive columns

API Security

• CORS: explicit allowed origins (never * in production)
• Security headers: X-Content-Type-Options, X-Frame-Options, CSP
• HTTPS enforced (redirect HTTP → HTTPS)
• API keys/secrets never logged or included in error messages
• 4xx errors don't reveal internal details (stack traces, file paths)

Dependency Security

• No known CVEs in dependencies (run: pip audit / npm audit)
• Dependencies pinned to exact versions
• Secrets never in code or git history (use env vars / secrets manager)
• .env files in .gitignore

Common Vulnerabilities to Check

OWASP Top 10:
1. Broken Access Control — can user A see/edit user B's data?
2. Cryptographic Failures — are secrets/passwords properly protected?
3. Injection — SQL, command, LDAP injection possible?
4. Insecure Design — is auth logic correct by design?
5. Security Misconfiguration — debug mode on? default credentials?
6. Vulnerable Components — any known CVEs in deps?
7. Auth Failures — session fixation? weak tokens?
8. Data Integrity — deserialization attacks? tampered JWTs?
9. Logging Failures — are attacks logged? are secrets in logs?
10. SSRF — can attacker make server fetch internal URLs?

Issue Format

For each finding: [CRITICAL|HIGH|MEDIUM|LOW] file.py:line — description — exact fix recommendation