Element Code: SE-008
Quick Reference
Issue: X-XSS-Protection header not set
Impact: Older browsers lack built-in XSS filtering
Fix: Add X-XSS-Protection: 1; mode=block
Detection: HTTP header inspection
What Is This Issue?
While modern browsers have deprecated this header in favor of CSP, older browsers still benefit from the built-in XSS filter it enables.
Why This Matters for Your Website
Legacy protection for older browsers. Modern sites should rely on CSP, but this provides backward compatibility.
How to Fix This Issue
- Add header: X-XSS-Protection: 1; mode=block
- Prioritize CSP: This is supplementary, not primary protection
Tools for Detection
- Security headers check: Verify X-XSS-Protection
TL;DR (The Simple Version)
Add X-XSS-Protection header for older browser protection. For modern browsers, focus on Content-Security-Policy instead.
Claude Vincent is a technical SEO consultant focused on crawlability, rendering, and AI-search visibility. He writes the field guides and case studies at SEO ProCheck, with a bias toward the durable, unglamorous work that decides whether search engines and AI answer engines can actually read and cite a site.
About SEO ProCheck
Technical SEO consulting and GEO strategy with 20 years of enterprise experience. Case studies, resources, and tools for search and AI visibility.
Work With Me
Technical SEO audits, GEO strategy, site migrations, and international SEO. Hourly consulting for teams who need hands-on support, not just reports.
Subscribe to our newsletter!
