Restrict where scripts can load from on nginx

Why it matters

The policy sets neither script-src nor default-src, so it does nothing against injected scripts, the main thing a CSP is for. Add a script-src that lists only your own origin and the services you use, or that uses nonces.

Staged change. Do this in stages and check each one before the next, so a mistake does not break your site or your mail.

The fix

1. Stage 1: add the line below next to your existing CSP, run sudo nginx -t and reload; check the developer console.
2. Stage 2: merge the directives into the enforced Content-Security-Policy and remove the report-only line.

add_header Content-Security-Policy-Report-Only "script-src 'self'; object-src 'none'; base-uri 'self'" always;

Read the documentation ↗(opens in a new tab)

Related

• Reported by the Content-Security-Policy check
• Add a Content-Security-Policy
• Enforce the report-only Content-Security-Policy
• Send the Content-Security-Policy as an HTTP header
• Replace 'unsafe-inline' scripts with nonces or hashes
• Remove 'unsafe-eval' from script-src
• Remove wildcard sources from script-src
• Set object-src to 'none'
• Add base-uri to the Content-Security-Policy
• Reduce reliance on inline styles
• Fix the Content-Security-Policy syntax