Description (CNA)
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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| traefik / traefik | affected < 2.11.43; affected >= 3.0.0-beta1, < 3.6.14; affected >= 3.7.0-ea.1, < 3.7.0-rc.2 |
CWE
CWE-290, CWE-306
References
- https://github.com/traefik/traefik/security/advisories/GHSA-5m6w-wvh7-57vm
- https://github.com/traefik/traefik/releases/tag/v2.11.43
- https://github.com/traefik/traefik/releases/tag/v3.6.14
- https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
ADP enrichment
No English description supplied.
No references supplied.
A flaw was found in Traefik. A remote attacker can exploit an authentication bypass vulnerability by injecting spoofed trust context through unsanitized alias headers. This is due to Traefik's forwarded-header sanitization logic not properly handling alias header names that use underscores instead of dashes. This allows an attacker to bypass authentication on protected routes without valid credentials.