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.
Affected products
traefik: traefik
References5
- github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8… PatchVendor Advisory
- github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2… Patch
- github.com/traefik/traefik/pull/13572 Patch
- github.com/traefik/traefik/releases/tag/v3.6.25 PatchRelease Notes
- github.com/traefik/traefik/releases/tag/v3.7.10 PatchRelease Notes
Metrics
- CVSS 3.1
-
3.8
LOW
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N - CVSS 4.0
-
2.1
LOW
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 27 · as of 12 November 2026
- CWE
- CWE-287
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.