Bug 2477938 (CVE-2026-41181)

Summary: CVE-2026-41181 traefik: Traefik: Information disclosure via errors middleware exposing user credentials
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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. The errors (custom error pages) middleware can inadvertently expose end-user credentials. When a backend returns a response matching a configured status range, the middleware forwards the original request's complete header set, including sensitive authentication material like Authorization and Cookie headers, to a separate error page service. This can lead to the disclosure of sensitive user credentials to infrastructure not intended to receive them.
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Description OSIDB Bzimport 2026-05-15 17:01:38 UTC 
Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.44, 3.6.15, and 3.7.0-rc.3, there is an information disclosure vulnerability in Traefik's errors (custom error pages) middleware. When the backend returns a response matching the configured status range, the middleware forwards the original request's complete header set, including Authorization, Cookie, and other authentication material, to the separate error page service rather than only the minimal context needed to render the error page. This behavior is undocumented: the documentation states only that Host is forwarded by default, so operators are not warned that sensitive credentials are shared across service boundaries. Deployments using the errors middleware with a distinct error page service may inadvertently expose end-user credentials to infrastructure that was not intended to receive them. This vulnerability is fixed in 2.11.44, 3.6.15, and 3.7.0-rc.3.