Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.57, and 3.7.13, Traefik accepts a rootless HTTP/1 request target that Go stores in URL.Opaque while leaving URL.Path empty. The rewriteRequestBuilder path evaluates routing, path sanitization, forwardAuth, encodedCharacters, and access logging against a path normalized to / but forwards URL.Opaque verbatim to the backend, allowing cross-vhost routing bypass, path-scoped authorization bypass, and access-log evasion when the backend interprets the opaque target as a path. This issue is fixed in 2.11.57 and 3.7.13.
https://github.com/traefik/traefik/security/advisories/GHSA-f52w-8j3h-j724
https://github.com/traefik/traefik/releases/tag/v3.7.13
https://github.com/traefik/traefik/releases/tag/v2.11.57
https://github.com/traefik/traefik/pull/13796
https://github.com/traefik/traefik/commit/58d1e9ca204526823211e30fd4634101c59d58e9
Published: 2026-09-10
Updated: 2026-09-10
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Severity: Medium
Base Score: 8.8
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00335