CVE-2026-71326

Description

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.

References

• https://github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2d9e08b7e350
• https://github.com/traefik/traefik/pull/13572
• https://github.com/traefik/traefik/releases/tag/v3.6.25
• https://github.com/traefik/traefik/releases/tag/v3.7.10
• https://github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8mrf