Description
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a high severity authentication bypass vulnerability in Traefik's ForwardAuth and snippet-based authentication middleware. Traefik's forwarded-header sanitization logic targets only canonical header names (e.g., X-Forwarded-Proto) and does not strip or normalize alias variants that use underscores instead of dashes (e.g., X_Forwarded_Proto). These unsanitized alias headers are forwarded intact to the authentication backend. When the backend normalizes underscore and dash header forms equivalently, an attacker can inject spoofed trust context — such as a trusted scheme or host — through the alias headers and bypass authentication on protected routes without valid credentials. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.
Problem types
CWE-290: Authentication Bypass by Spoofing
CWE-306: Missing Authentication for Critical Function
Product status
>= 3.0.0-beta1, < 3.6.14
>= 3.7.0-ea.1, < 3.7.0-rc.2
References
github.com/...raefik/security/advisories/GHSA-5m6w-wvh7-57vm
github.com/traefik/traefik/releases/tag/v2.11.43
github.com/traefik/traefik/releases/tag/v3.6.14
github.com/traefik/traefik/releases/tag/v3.7.0-rc.2