CVE-2026-88011
highTraefik is an open source HTTP reverse proxy and load balancer.
Vendor / product: Traefik — traefik
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 while normalization-prone CGI, WSGI, PHP, and NGINX backends collapse both names. A backend can consequently consume the client value instead of the identity Traefik asserted, allowing identity spoofing for any header managed by Traefik. The aliasHeadersStrategy protection is disabled by default and must be configured as delete or reject. The mitigation is available in 2.11.56 and 3.7.12.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Affected products
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
References
- https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbecf8 security-advisories@github.com
- https://github.com/traefik/traefik/pull/13720 security-advisories@github.com
- https://github.com/traefik/traefik/releases/tag/v2.11.56 security-advisories@github.com
- https://github.com/traefik/traefik/releases/tag/v3.7.12 security-advisories@github.com
- https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8c security-advisories@github.com