Authentication bypass in StripPrefix middleware allows unauthorized access to protected paths

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. A flaw was found in Traefik, an HTTP reverse proxy and load balancer. This vulnerability exists in the StripPrefix middleware, allowing an unauthenticated attacker to bypass route-level authentication and authorization. By crafting a request path containing '..' or its percent-encoded form, an attacker can access protected backend paths, such as administrative or internal configuration endpoints, without proper authentication. This could lead to unauthorized information disclosure or modification of sensitive settings. This is an Important authentication bypass flaw in Traefik's StripPrefix middleware, affecting Red Hat OpenShift Dev Spaces. An unauthenticated remote attacker can exploit this by crafting a specific request path, gaining access to protected backend resources like administrative or internal configuration endpoints. This could lead to unauthorized information disclosure or modification of sensitive settings. Red Hat severity: Important — CVSS 9.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N). Weakness: CWE-22. No fixing RHSA erratum has published yet; monitor the Red Hat CVE page and patch when it ships.