Traefik StripPrefix Route-Level Auth Bypass via Path Normalization

Summary

Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. This vulnerability is fixed in 2.11.48, 3.6.19, and 3.7.3.

Timeline

1. Jun 23, 2026, 7:10 PM UTCCVE published
2. Jun 24, 2026, 1:37 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Sep 2, 2026, 12:04 PM UTCRecord last updated

Affected versions

• traefik traefik

  From 3.7.0-ea.1 · fixed in 3.7.3; From 3.0.0-beta1 · fixed in 3.6.19; fixed in 2.11.48

• github.com/traefik/traefik/v2Go

  fixed in 2.11.48

• github.com/traefik/traefik/v3Go

  fixed in 3.6.19

• github.com/traefik/traefik/v3Go

  From 3.7.0-ea.1 · fixed in 3.7.3

• github.com/traefik/traefikGo

  All versions

• github.com/traefik/traefik/v3Go

  fixed in 3.6.19; From 3.7.0-ea.1 · fixed in 3.7.3

References 5