Traefik up to 3.6.24/3.7.9 BasicAuth Middleware basic_auth.go improper authentication

Summaryinfo

A vulnerability classified as critical has been found in Traefik up to 3.6.24/3.7.9. Impacted is an unknown function of the file pkg/middlewares/auth/basic_auth.go of the component BasicAuth Middleware. This manipulation causes improper authentication. This vulnerability is registered as CVE-2026-71326. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability classified as critical was found in Traefik up to 3.6.24/3.7.9. Affected by this vulnerability is some unknown processing of the file pkg/middlewares/auth/basic_auth.go of the component BasicAuth Middleware. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Traefik is an open source HTTP reverse proxy and load balancer. From 3.6.11 until 3.6.25 and 3.7.10, Traefik's BasicAuth middleware in pkg/middlewares/auth/basic_auth.go deduplicates concurrent password checks with a singleflight key built from the delimiter-free concatenation of password and secret, allowing an attacker who has a valid credential and the stored hash to authenticate as an unconfigured username when headerField trusts the forwarded identity. This issue is fixed in 3.6.25 and 3.7.10.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-71326 since 08/05/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.6.25 or 3.7.10 eliminates this vulnerability.

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Productinfo

Name

• Traefik

Version

• 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
• 3.6.14
• 3.6.15
• 3.6.16
• 3.6.17
• 3.6.18
• 3.6.19
• 3.6.20
• 3.6.21
• 3.6.22
• 3.6.23
• 3.6.24
• 3.7.0
• 3.7.1
• 3.7.2
• 3.7.3
• 3.7.4
• 3.7.5
• 3.7.6
• 3.7.7
• 3.7.8
• 3.7.9

Website

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

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