Enterprise Next.js Security: Content Security Policies, Secrets & Edge Defense

## The Reality of Web Application Security Modern web development frameworks provide incredible speed, but default configurations frequently leave dangerous security gaps. As applications integrate more third-party tracking scripts, AI APIs, and user-generated content, the attack surface expands dramatically. ## 1. Strict Content Security Policy (CSP) Level 3 A robust CSP header prevents cross-site scripting (XSS) and malicious script injection by restricting where scripts, styles, and fonts can load from: ```http Content-Security-Policy: default-src 'self'; script-src 'self' 'nonce-rAnd0m123'; object-src 'none'; frame-ancestors 'none'; ``` ## 2. Environment Secret Isolation Never expose sensitive database credentials or internal API tokens to client bundles. In Next.js, ensure only public variables use the `NEXT_PUBLIC_` prefix, while database connection pools and private keys remain strictly server-isolated. ## 3. Automated Dependency & Secret Scanning Integrate pre-commit hooks and CI/CD secret scanning (Trivy, Semgrep, Gitleaks) to prevent accidental API key commits to public Git repositories. ### The HarLyn Standard Every website we engineer is audited against the OWASP Top 10 framework before DNS propagation.