- Add Helmet with CSP, HSTS, referrer policy - Configure CORS with environment-based origins - Add global validation pipe with whitelist mode - Add SanitizeInputMiddleware for XSS prevention - Add ThrottlerBehindProxyGuard for rate limiting - Add FileValidationPipe for upload security - Set request body size limit to 1MB Co-Authored-By: Paperclip <noreply@paperclip.ing>