Auth bypass in Traefik
CVE-2026-71326
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.8 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (27.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Traefik — versions >= 3.6.11, < 3.6.25, >= 3.7.0, < 3.7.10
Weakness classification (CWE)
References
- github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2d9e08b7e350 (Patch)
- github.com/traefik/traefik/pull/13572 (Patch)
- github.com/traefik/traefik/releases/tag/v3.6.25 (Patch, Release Notes)
- github.com/traefik/traefik/releases/tag/v3.7.10 (Patch, Release Notes)
- github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8mrf (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-71326?
- CVE-2026-71326 is a low-severity vulnerability in Traefik, classified under Improper Authentication. CVSS score: 3.8/10. Published 2026-08-06.
- How severe is CVE-2026-71326?
- Low severity. CVSS v3 base score is 3.8 out of 10.