Bug 2531505 (CVE-2026-88009)

Summary: CVE-2026-88009 github.com/traefik/traefik: Traefik: Authorization bypass and access-log evasion via crafted HTTP/1 request
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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 open source HTTP reverse proxy and load balancer. This vulnerability allows a remote attacker to bypass security controls by sending a specially crafted HTTP/1 request. The request target is incorrectly processed, leading to cross-vhost routing bypass, path-scoped authorization bypass, and access-log evasion. This can occur when the backend server interprets the opaque request target as a valid path.
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Description OSIDB Bzimport 2026-09-10 15:23:19 UTC 
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.