https://db.gcve.eu/rss/recent/all/10 Most recent entries from all 2026-10-01T15:53:51.568376+00:00 Vulnerability-Lookup info@gcve.eu python-feedgen Contains only the most 10 recent entries. https://db.gcve.eu/vuln/fkie_cve-2026-88011 fkie_cve-2026-88011 2026-10-01T15:53:51.586003+00:00

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.

 https://db.gcve.eu/vuln/ghsa-rf44-j88r-hh8c GHSA-rf44-j88r-hh8c — Traefik: ForwardAuth identity spoofing via dot-form header alias 2026-10-01T15:53:51.586073+00:00

Affected: Go: github.com/traefik/traefik/v2, Go: github.com/traefik/traefik/v3

## 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 names from header names (CGI, WSGI, PHP, NGINX, and others) collapse all of them into the same variable. A client can therefore smuggle an alias of a header that Traefik manages past the middleware managing it — for example a dot-form `X.Authenticated.User` alongside the canonical `X-Authenticated-User` written by the ForwardAuth middleware — and have such a backend read the client-supplied value instead of the identity Traefik asserted. Any header Traefik sets is exposed, not only ForwardAuth's. This is an incomplete-fix sibling of GHSA-x677-9fxg-v5c5, which blocked only the underscore form.

The mitigation is the new `aliasHeadersStrategy` entry point option. It defaults to `keep`, which preserves the previous behavior for backwards compatibility, so it must be explicitly set to `delete` or `reject` to take effect.

Traefik v1.x, the v2 releases up to v2.11.55 and the v3 releases from v3.0.0 to v3.7.11 are affected. The unmaintained lines among them will not receive a patch of their own, and the remedy for their users is to upgrade to v2.11.56 or v3.7.12 and set `aliasHeadersStrategy`.

## Patches

- https://github.com/traefik/traefik/releases/tag/v2.11.56 - https://github.…