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.
https://github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8mrf
https://github.com/traefik/traefik/releases/tag/v3.7.10
https://github.com/traefik/traefik/releases/tag/v3.6.25
https://github.com/traefik/traefik/pull/13572
https://github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2d9e08b7e350
Published: 2026-08-06
Updated: 2026-08-06
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 9.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Severity: Critical
Base Score: 2.1
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Severity: Low
EPSS: 0.00356