Node.js Security
📌 Covered in this chapter:
Input Validation · XSS/Injection Prevention · CORS · Helmet · Rate Limiting
Harden your Node.js and Express applications against common attacks: XSS, injection, CSRF, and misconfigured CORS.
1Node.js Security — What You'll Learn
Harden your Node.js and Express applications against common attacks: XSS, injection, CSRF, and misconfigured CORS.
Here's everything this chapter covers, in the order you'll learn it:
- Input validation as your first line of defense
- XSS (Cross-Site Scripting) prevention
- SQL injection prevention
- NoSQL injection prevention
- CSRF basics
- CORS (Cross-Origin Resource Sharing) configuration
- The Helmet middleware for secure HTTP headers
- Rate limiting to prevent abuse
- Secure cookie settings
- Password security
- Keeping secrets out of your code (environment variables)
- Auditing dependencies for known vulnerabilities
- Security headers
- Logging without leaking sensitive data
2Working Example
💻 Example: Node.js Security
JavaScript
▶ Run in Compiler
import helmet from "helmet";
import rateLimit from "express-rate-limit";
app.use(helmet());
app.use(rateLimit({ windowMs: 15 * 60 * 1000, max: 100 }));3Best Practices & Common Pitfalls
💡 Key things to remember:
- Run `npm audit` regularly to catch known vulnerabilities in your dependencies before they reach production.
- Helmet sets a collection of secure-by-default HTTP headers with a single line — a strong baseline for any Express app.
❓ Frequently Asked Questions (FAQ)
Q What's the most important thing to understand about node.js security?
Focus on: Input Validation · XSS/Injection Prevention · CORS · Helmet · Rate Limiting. These are the core building blocks this chapter's examples are built around, and they show up repeatedly in later chapters of this course.
Q Do I need external npm packages for node.js security?
Only where explicitly shown in the code examples above (like Express, Zod, or Socket.IO) — otherwise, this chapter relies entirely on Node.js's own built-in capabilities.