Direct Answer: What is RFC 9116 security.txt?
RFC 9116 is the official IETF standard specification that mandates how websites disclose their security reporting policies. By placing a plain-text security.txt file at /.well-known/security.txt, organizations provide ethical security researchers and white-hat bug hunters with authenticated contact channels (Contact: mailto:... or HTTPS web forms), policy guidelines (Policy: https://...), and an mandatory expiration date (Expires: 2027-10-01...). This prevents lost vulnerability notices, reduces legal ambiguities with Safe Harbor provisions, and protects website infrastructure from undisclosed zero-day exploits.
RFC 9116 Directives Specification Matrix
Standard compliance requirements, formats, and placement guidelines
| Directive | Requirement Level | Format / Syntax | Purpose |
|---|---|---|---|
| Contact | Mandatory | mailto:user@domain or https://... | Direct email address or bug bounty portal for vulnerability intake. |
| Expires | Mandatory | ISO 8601 (e.g. 2027-10-01T00:00:00+00:00) | Expiration timestamp to ensure security policies remain actively maintained. |
| Encryption | Optional | https://... (PGP Key URL) | Public PGP/GPG key for end-to-end encrypted vulnerability report submissions. |
| Canonical | Optional | https://domain.com/.well-known/security.txt | Authoritative URL to guard against cache poisoning and proxy tampering. |
| Policy | Optional | https://... (Policy URL) | Rules of engagement and Safe Harbor legal protection terms for researchers. |