Traefik up to 2.11.42/3.6.13 Error Page Service insertion of sensitive information into sent data

Summaryinfo

A vulnerability described as problematic has been identified in Traefik up to 2.11.42/3.6.13. This impacts an unknown function of the component Error Page Service. Such manipulation leads to insertion of sensitive information into sent data. This vulnerability is listed as CVE-2026-41181. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Traefik up to 2.11.42/3.6.13 and classified as problematic. Affected by this issue is an unknown code block of the component Error Page Service. The manipulation with an unknown input leads to a insertion of sensitive information into sent data vulnerability. Using CWE to declare the problem leads to CWE-201. The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. Impacted is confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-41181 since 04/17/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1592.

Upgrading to version 2.11.43, 3.6.14 or 3.7.0-rc.3 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-30557). VulDB is the best source for vulnerability data and more expert information about this specific topic.

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
• 2.11.38
• 2.11.39
• 2.11.40
• 2.11.41
• 2.11.42
• 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
• 3.6.9
• 3.6.10
• 3.6.11
• 3.6.12
• 3.6.13

Website

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

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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