GO-2026-6455 Traefik: ForwardAuth identity spoofing via dot-form header alias in github.com/traefik/traefik

Traefik: ForwardAuth identity spoofing via dot-form header alias in github.com/traefik/traefik...

CVE-2026-88011

Traefik 's ForwardAuth middleware is vulnerable to identity spoofing via dot-form header aliases (e.g. X.Authenticated.User). Go treats these as distinct from the canonical dash-form header, but backends such as PHP, CGI, WSGI, and NGINX collapse both into the same variable, allowing a permitted ...

CVE-2026-88011 Traefik: ForwardAuth identity spoofing via dot-form header alias

Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User...

CVE-2026-88879

Traefik (HTTP reverse proxy and load balancer) is vulnerable to identity spoofing via dot-form header aliasing in versions v1.x, v2.x–v2.11.55, and v3.0.0–v3.7.11. Because Go canonicalizes header names on dashes only, a client can send a dot-form alias (e.g., X.Authenticated.User) alongside the c...

CVE-2026-88879 Traefik before v2.11.56 Identity Spoofing via Header Alias

Traefik is an HTTP reverse proxy and load balancer. In Traefik v1.x, v2.x through v2.11.55, and v3.0.0 through v3.7.11, header names are canonicalized only on dashes, so X-Auth-User, XAuthUser and X.Auth.User are treated as three distinct headers by Traefik, while backends that derive variable...

CVE-2026-88879 Traefik before v2.11.56 Identity Spoofing via Header Alias

Traefik is an HTTP reverse proxy and load balancer. In Traefik v1.x, v2.x through v2.11.55, and v3.0.0 through v3.7.11, header names are canonicalized only on dashes, so X-Auth-User, XAuthUser and X.Auth.User are treated as three distinct headers by Traefik, while backends that derive variable...

PT-2026-89699

Summary There is a medium severity vulnerability in Traefik's handling of request headers whose name aliases another header name. Go canonicalizes header names on dashes only, so X-Auth-User, X Auth User and X.Auth.User are three distinct headers to Traefik, while backends that derive variable...

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...