Improper Handling of Case Sensitivity in Traefik - CVE-2026-29054
Published: May 5, 2026
Vulnerability identifier: #VU129666
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-29054
CWE-ID: CWE-178
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Containous
Affected software:
Traefik
Traefik
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass downstream header-based authentication, authorization, routing, or scheme decisions.
The vulnerability exists due to improper handling of case sensitivity in the XForwarded middleware removeConnectionHeaders function when processing HTTP/1.1 requests with client-supplied Connection header tokens. A remote attacker can send a specially crafted request with lowercase Connection tokens to bypass downstream header-based authentication, authorization, routing, or scheme decisions.
This issue can remove Traefik-managed forwarded identity headers such as X-Real-Ip and X-Forwarded-* before they reach downstream services.
How to mitigate CVE-2026-29054
Install security update from vendor's website.