| name | react-security |
| description | Security practices for React (XSS, Auth, Dependencies). Use when preventing XSS, securing auth flows, or auditing third-party dependencies in React. (triggers: **/*.tsx, **/*.jsx, dangerouslySetInnerHTML, token, auth, xss) |
React Security
Priority: P0 (CRITICAL)
Preventing vulnerabilities in client-side apps.
Implementation Guidelines
- XSS Prevention: Never use
dangerouslySetInnerHTML without sanitization. Use DOMPurify.sanitize(input) for all user-provided HTML. Avoid javascript: protocols in href or src.
- Authentication: Store JWT/Sessions in
HttpOnly and Secure cookies to prevent theft via XSS. Never store secrets in localStorage or in the built JS bundle.
- Data Flow: Escape all serialized state if injecting into the HTML (e.g., in SSR). Use a Content Security Policy (CSP) to restrict script sources and prevent inline execution.
- CSRF Protection: Use CSRF tokens for state-changing requests (PUT/POST/DELETE). Implement SameSite=Strict cookies where applicable.
- Input Sanitization: Always validate and sanitize user inputs on the backend. Frontend validation is for UX only.
- Dependency Management: Run
npm audit / pnpm audit regularly. Pin specific dependency versions and use npm-check-updates.
- Security Headers: Ensure the server sends
X-Frame-Options: DENY, X-Content-Type-Options: nosniff, and Permissions-Policy.
Anti-Patterns
- No
eval(): RCE risk.
- No Serialized State: Don't inject JSON into DOM without escaping.
- No Client Logic for Permissions: Backend must validate.
References
See references/REFERENCE.md for DOMPurify usage, CSP headers, OAuth2/JWT auth patterns, and CSRF protection.
