Traefik v3.7.1 crossProviderNamespaces Bypass via Service Middleware

Description

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.

Scores

EPSS (exploitation in 30 days)

0.48% · top 59% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.0.

Weakness

• CWE-639: Authorization Bypass Through User-Controlled Key (opens in a new tab)All about CWE-639 and its CVEs

Affected products

• traefik · traefik

  • affected 3.7.1 – ≤ 3.7.12

References (2)

• GitHub Security Advisory (GHSA-m6wx-622r-48r9) (opens in a new tab)vendor-advisory
• VulnCheck Advisory: Traefik v3.7.1 crossProviderNamespaces Bypass via Service Middleware (opens in a new tab)third-party-advisory

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-85594](https://trackcve.app/badge/CVE-2026-85594.svg)](https://trackcve.app/cve/CVE-2026-85594)

Record last updated 8 Oct 2026, 15:51 UTC.