Authentication Bypass

github.com/traefik/traefik is vulnerable to an authentication bypass. The vulnerability is due to improper sanitization of forwarded header alias variants using underscores instead of dashes, which allows an attacker to inject spoofed trusted headers and bypass authentication on protected routes...

CVE-2026-39858

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...

GHSA-5M6W-WVH7-57VM Traefik: Pre-authentication decision bypass due to forwarded alias spoofing

Summary 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...