What’s Vulnerable › Vulnerabilities

CVE-2026-85594: Traefik v3.7.1 crossProviderNamespaces Bypass via Service Middleware

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-04 · updated 2026-10-08
• Weakness: CWE-639

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.

Affected products

• Traefik: before 3.7.11 — fixed in 3.7.11

How to fix

Upgrade to a fixed version: Traefik 3.7.11. Check the vendor advisory for mitigations.

References

• https://github.com/traefik/traefik/security/advisories/GHSA-m6wx-622r-48r9
• https://www.vulncheck.com/advisories/traefik-3.7.1-crossprovidernamespaces-bypass-via-service-middleware

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