Traefik up to 2.11.37/3.6.8 Reverse Proxy case sensitivity

Summaryinfo

A vulnerability was found in Traefik up to 2.11.37/3.6.8. It has been declared as problematic. This affects an unknown function of the component Reverse Proxy Handler. The manipulation results in case sensitivity. This vulnerability is identified as CVE-2026-29054. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Traefik up to 2.11.37/3.6.8. Affected is some unknown processing of the component Reverse Proxy Handler. The manipulation with an unknown input leads to a case sensitivity vulnerability. CWE is classifying the issue as CWE-178. The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results. This is going to have an impact on integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-29054 since 03/03/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 318670 (Traefik 2.11.x < 2.11.38 / 3.x < 3.6.9 Connection Header Bypass), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.11.38 or 3.6.9 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (318670). Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• Traefik

Version

• 2.11.0
• 2.11.1
• 2.11.2
• 2.11.3
• 2.11.4
• 2.11.5
• 2.11.6
• 2.11.7
• 2.11.8
• 2.11.9
• 2.11.10
• 2.11.11
• 2.11.12
• 2.11.13
• 2.11.14
• 2.11.15
• 2.11.16
• 2.11.17
• 2.11.18
• 2.11.19
• 2.11.20
• 2.11.21
• 2.11.22
• 2.11.23
• 2.11.24
• 2.11.25
• 2.11.26
• 2.11.27
• 2.11.28
• 2.11.29
• 2.11.30
• 2.11.31
• 2.11.32
• 2.11.33
• 2.11.34
• 2.11.35
• 2.11.36
• 2.11.37
• 3.6.0
• 3.6.1
• 3.6.2
• 3.6.3
• 3.6.4
• 3.6.5
• 3.6.6
• 3.6.7
• 3.6.8

Website

• Product: https://github.com/traefik/traefik/

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Once again VulDB remains the best source for vulnerability data.

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