Bug 2491915 (CVE-2026-48020)

Summary: CVE-2026-48020 github.com/traefik/traefik: Traefik: Authentication bypass in StripPrefix middleware allows unauthorized access to protected paths
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: sdawley
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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.
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Description OSIDB Bzimport 2026-06-23 20:01:20 UTC 
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.