CVE-2026-88009: Traefik

High severity, CVSS 8.2. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Traefik Traefik: before 2.11.57 (fixed in 2.11.57); from 3.0.0, before 3.7.13 (fixed in 3.7.13)

Published 2026-09-10. Last modified 2026-09-14.