Auth bypass in Traefik
CVE-2026-85594
Traefik versions from v3.7.1 fail to enforce crossProviderNamespaces restrictions on the traefik.ingress.kubernetes.io/service.middlewares Service annotation in the Kubernetes Ingress provider. A namespace-limited tenant excluded from the allowlist can attach an operator-owned middleware to its Service, and if that middleware injects backend credentials, recover them at a controlled backend.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.9% 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: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- github.com/traefik/traefik/security/advisories/GHSA-m6wx-622r-48r9 (Exploit, vendor-advisory, Patch, Vendor Advisory)
- www.vulncheck.com/advisories/traefik-3.7.1-crossprovidernamespaces-bypass-via-s… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-85594?
- CVE-2026-85594 is a critical-severity vulnerability in Traefik, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 9.8/10. Published 2026-09-04.
- How severe is CVE-2026-85594?
- Critical severity. CVSS v3 base score is 9.8 out of 10.