Next.js 14 Security Best Practices for Enterprise

Next.js 14 introduced Server Actions, changing how we think about backend logic. While powerful, it opens new vectors for vulnerabilities if not handled correctly.

1. Input Validation is Non-Negotiable

Just because it's running on the server doesn't mean the input is safe. Always use libraries like Zod to validate schema before processing any action.

2. Authentication vs. Authorization

Knowing who the user is (AuthN) is different from knowing what they can do (AuthZ). We recommend using middleware for route protection and per-action checks for data mutation.

3. Content Security Policy (CSP)

A strict CSP is your last line of defense against XSS. In the app router, this can be configured via middleware headers.