CVE-2026-39858
traefik: Traefik: Authentication bypass via unsanitized alias headers
Severidad por fuente
La etiqueta propia de Trivy es CRITICAL. Crítica según NVD. Más baja según GHSA (alta), Red Hat (alta).
Descripción
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.
Paquetes afectados y versiones corregidas
| Fuente | Paquete | Corregido en |
|---|---|---|
| go::GitHub Security Advisory Go | github.com/traefik/traefik, github.com/traefik/traefik/v2, github.com/traefik/traefik/v3 | 2.11.43 y 1 más |
| minimos | traefik-3, traefik-fips-3 | 3.6.14-r0 |
| rapidfort alpine 3.20 | traefik | 3.7.0-r0 |
| rapidfort alpine 3.21 | traefik | 3.7.0-r0 |
| rapidfort alpine 3.22 | traefik | 3.7.0-r0 |
| rapidfort alpine 3.23 | traefik | 3.7.0-r0 |
Mostrar las 9 entradas de 6 fuentes
| Fuente | Paquete | Corregido en |
|---|---|---|
| go::GitHub Security Advisory Go | github.com/traefik/traefik | sin corrección indicada |
| go::GitHub Security Advisory Go | github.com/traefik/traefik/v2 | 2.11.43 |
| go::GitHub Security Advisory Go | github.com/traefik/traefik/v3 | 3.7.0-rc.2, 3.6.14 |
| minimos | traefik-3 | 3.6.14-r0 |
| minimos | traefik-fips-3 | 3.6.14-r0 |
| rapidfort alpine 3.20 | traefik | 3.7.0-r0 |
| rapidfort alpine 3.21 | traefik | 3.7.0-r0 |
| rapidfort alpine 3.22 | traefik | 3.7.0-r0 |
| rapidfort alpine 3.23 | traefik | 3.7.0-r0 |
Referencias
- https://access.redhat.com/errata/RHSA-2026:21772
- https://access.redhat.com/security/cve/CVE-2026-39858
- https://bugzilla.redhat.com/show_bug.cgi?id=2464234
- https://github.com/traefik/traefik
- 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
- https://github.com/traefik/traefik/security/advisories/GHSA-5m6w-wvh7-57vm