Website SecurityInformational 7 min read Last reviewed: 2026-10-18
HTTP Security Headers Explained: CSP, HSTS, X-Frame-Options & Referrer-Policy for UK Websites
Missing HTTP security headers leave websites vulnerable to clickjacking, XSS script injection, and SSL stripping. Learn how to inspect and deploy production headers in Next.js, Nginx, and Cloudflare.
Written by Eleanor Sterling (Head of Threat Intelligence, HackGuardX UK)
Primary Topic: http security headers guide
Executive Key Takeaways
- Strict-Transport-Security (HSTS) forces browsers to connect exclusively over HTTPS, preventing downgrade attacks.
- Content-Security-Policy (CSP) restricts where scripts can load from, blocking Magecart checkout skimmers and XSS.
- X-Frame-Options and frame-ancestors prevent attackers from embedding your login page inside an invisible iframe.
1. Why Valid SSL Is Not Enough
Every modern website has an HTTPS certificate, yet over 75% of UK SME websites fail basic HTTP security header checks. Security headers are lightweight instructions sent by your web server that tell the customer's browser how to defend against cross-site scripting (XSS), clickjacking, and MIME-type sniffing.
2. Copy-Paste Header Configuration
Below is a baseline production security header configuration suitable for Next.js, Nginx, or Cloudflare Transform Rules:
Actionable Implementation Checklist:
✓Strict-Transport-Security: max-age=63072000; includeSubDomains; preload
✓X-Content-Type-Options: nosniff
✓X-Frame-Options: DENY
✓Referrer-Policy: strict-origin-when-cross-origin
✓Permissions-Policy: camera=(), microphone=(), geolocation=()
Official UK & International Standards Referenced
Put This Guide Into Practice
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