Bug 2444872 (CVE-2026-29054)

Summary: CVE-2026-29054 github.com/traefik/traefik: Traefik: Information disclosure due to case-insensitive Connection header processing
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 HTTP reverse proxy and load balancer. A remote unauthenticated client can exploit a case sensitivity vulnerability in how Traefik processes HTTP/1.1 requests. By using lowercase tokens in the Connection header, an attacker can bypass security protections, leading to the removal of Traefik-managed forwarded identity headers. This could result in information disclosure or misattribution of client requests.
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Description OSIDB Bzimport 2026-03-05 19:01:27 UTC 
Traefik is an HTTP reverse proxy and load balancer. From version 2.11.9 to 2.11.37 and from version 3.1.3 to 3.6.8, there is a potential vulnerability in Traefik managing the Connection header with X-Forwarded headers. When Traefik processes HTTP/1.1 requests, the protection put in place to prevent the removal of Traefik-managed X-Forwarded headers (such as X-Real-Ip, X-Forwarded-Host, X-Forwarded-Port, etc.) via the Connection header does not handle case sensitivity correctly. The Connection tokens are compared case-sensitively against the protected header names, but the actual header deletion operates case-insensitively. As a result, a remote unauthenticated client can use lowercase Connection tokens (e.g. Connection: x-real-ip) to bypass the protection and trigger the removal of Traefik-managed forwarded identity headers. This issue has been patched in versions 2.11.38 and 3.6.9.