CVE-2026-71324

Description

Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.53, 3.6.24, and 3.7.9, Traefik's default HTTP reverse proxy forwards a plain HTTP/2 or HTTP/3 CONNECT request and its body to an HTTP/1.1 upstream through a shared net/http.Transport. When the upstream answers the CONNECT with a keep-alive non-2xx response and does not drain the body, Traefik returns the desynchronized backend socket to its shared pool and reuses it for other clients. An unauthenticated attacker can use this behavior to make a different client read the attacker's smuggled response, which can include authenticated or private content from another request. The ForwardAuth middleware with forwardBody true and preserveRequestMethod true can re-issue a CONNECT with the buffered body attached, exposing the auth-client pool to the same desynchronization. This issue is fixed in 2.11.53, 3.6.24, and 3.7.9.

References

https://github.com/traefik/traefik/security/advisories/GHSA-3ccp-42pg-hgv6

https://github.com/traefik/traefik/releases/tag/v3.7.9

https://github.com/traefik/traefik/releases/tag/v3.6.24

https://github.com/traefik/traefik/releases/tag/v2.11.53

https://github.com/traefik/traefik/pull/13556

https://github.com/traefik/traefik/pull/13543

https://github.com/traefik/traefik/pull/13542

https://github.com/traefik/traefik/commit/94a7508817d180f0ab2f1eae93df48d4ab19ecce

https://github.com/traefik/traefik/commit/0807b6d5dd1da8b2f7f4076ea2392b5437bf2ab0

https://github.com/traefik/traefik/commit/04d36f28e4eae7535e96a6351dd9f7bfb48a30e7

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS