Skip to content
CyberLens AI

Remediation guide

How to fix missing security headers in your web app

Published by CyberLens AI. Last updated .

Missing security headers are one of the most common website security findings — and one of the fastest to fix.

Add five one-line directives to your server or deployment config and you eliminate a whole category of browser-based attacks before your next deploy.

Check your headers now More fix guides

What security headers do

HTTP security headers are directives your server sends in every HTTP response. They tell the browser which origins to trust, whether to allow embedding, and whether to enforce HTTPS. Missing headers expose users to SSL-stripping, clickjacking, MIME-sniffing exploits, and cross-site scripting.

  • Strict-Transport-Security: forces HTTPS for all future visits
  • X-Content-Type-Options: nosniff — prevents MIME type confusion attacks
  • X-Frame-Options: DENY — blocks clickjacking via iframe embedding
  • Referrer-Policy: limits URL leakage in cross-origin requests
  • Permissions-Policy: disables browser features your app does not use
  • Content-Security-Policy: restricts script and resource loading (add last, requires tuning)

Add headers by platform

Copy the snippet for your deployment platform. These examples add five low-risk headers safe to deploy without testing against your specific app.

  • Vercel: add a headers block in vercel.json with source "/(.*)"
  • Express / Node.js: install helmet and call app.use(helmet()) early in middleware
  • Nginx: add add_header directives inside your server {} block
  • Apache: add Header always set directives in .htaccess or VirtualHost config

Verify the fix after deploying

Confirm headers are live using any of these methods.

  • Run a free CyberLens AI scan at cyberlensai.com/scan
  • Use curl -I https://your-domain.com from a terminal
  • Check the Network tab in browser DevTools under Response Headers

Questions and answers

Which security header should I add first?

Start with Strict-Transport-Security, X-Content-Type-Options, and X-Frame-Options. They take one line each and rarely cause regressions. Add Content-Security-Policy last — it is the most impactful but requires tuning to avoid breaking your own scripts and styles.

Can adding security headers break my site?

HSTS, nosniff, X-Frame-Options, Referrer-Policy, and Permissions-Policy almost never break things. Content-Security-Policy can break pages that use inline scripts, inline styles, or third-party embeds if you set it too strictly. Test a restrictive CSP in report-only mode first.

Why doesn't my AI-generated app have security headers?

AI code generators focus on producing working functional code. Security hardening — especially deployment-level config like response headers — does not appear in a working local demo, so it is easy to ship without. A security scan before launch catches these gaps.

How do I check if my headers are working after I deploy?

Run a free CyberLens AI scan, use curl -I https://your-domain.com from a terminal, or check the Network tab in browser DevTools. Each approach shows the raw HTTP response headers your server is sending.

Is Content-Security-Policy required?

Not required but strongly recommended for any app that accepts user input or loads third-party scripts. It is the most effective browser-side defense against cross-site scripting. Configure it last, after the other five headers are in place.

Security references

CyberLens AI guidance is informed by established security standards and public vulnerability intelligence.