Security Headers Check

Grade the HTTP security headers of any website. No signup required.

Prerequisites

• Playwright MCP (comes with Claude Code)

Trigger

• "Check security headers on https://..."
• "Security headers scan mysite.com"
• "Is my site missing any security headers?"

Workflow

1. Navigate to the URL using mcp__playwright__browser_navigate
2. Capture network response headers using mcp__playwright__browser_network_requests
3. Check each header category below against the captured response headers

Headers to Check

Content-Security-Policy (CSP)

• Should be present
• Should not contain unsafe-inline without a nonce or hash
• Should not contain unsafe-eval
• Should not use wildcard * in script-src or object-src

Strict-Transport-Security (HSTS)

• Should be present on HTTPS sites
• max-age should be ≥ 31536000 (1 year)
• Should include includeSubDomains
• preload is a bonus

X-Frame-Options

• Should be DENY or SAMEORIGIN
• (Note: CSP frame-ancestors supersedes this; award credit if CSP has it)

X-Content-Type-Options

• Should be nosniff

Referrer-Policy

• Should be present
• Recommended values: strict-origin-when-cross-origin, no-referrer, same-origin
• Penalize: unsafe-url, missing entirely

Permissions-Policy

• Should be present (formerly Feature-Policy)
• Should restrict at minimum: camera, microphone, geolocation

4. Grade the site:

5. Output:

## Security Headers Report: [URL]

**Grade: C** (3/6 headers configured correctly)

### Issues
1. [MISSING] Content-Security-Policy
   No CSP found. XSS attacks are not mitigated at the header level.

2. [WEAK] Strict-Transport-Security
   Found: max-age=3600
   Issue: max-age too short (3600s). Minimum recommended: 31536000 (1 year)
   Fix:   Strict-Transport-Security: max-age=31536000; includeSubDomains

3. [MISSING] Permissions-Policy
   No Permissions-Policy found. Browser features unrestricted.

### Passed
- X-Frame-Options: SAMEORIGIN ✓
- X-Content-Type-Options: nosniff ✓
- Referrer-Policy: strict-origin-when-cross-origin ✓

### Quick Fix (copy-paste for most servers)
Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
Permissions-Policy: camera=(), microphone=(), geolocation=()

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