substack.com

Score 45/100 · scanned 2026-08-04

Content-Security-Policy

substack.com sends an enforcing CSP. It is allowlist-based.

frame-ancestors 'self' https://*.substack.com https://substack.com

Directive	Sources
`frame-ancestors`	`'self' https://*.substack.com https://substack.com`

Headers sent

Header	Value
`strict-transport-security`	`max-age=31536000; includeSubDomains; preload`
`server`	`cloudflare`
`x-powered-by`	`Express`

Critical findings

No script-src and no default-src, so the policy places no restriction on scripts at all.Add script-src with a nonce or hash, or at minimum default-src 'self'.

Re-scan live

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