High [CVE-2026-85594] Information disclosure via crossProviderNamespaces bypass in Kubernetes Ingress provider
This high-severity Red Hat Linux advisory covers CVE-2026-85594.
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Summary
A flaw was found in Traefik. The software fails to enforce `crossProviderNamespaces` restrictions on the `traefik.ingress.kubernetes.io/service.middlewares` Service annotation within the Kubernetes Ingress provider.
This vulnerability allows a namespace-limited tenant, even if excluded from the allowlist, to attach an operator-owned middleware to its Service. If this middleware injects backend credentials, the tenant can then recover these credentials at a controlled backend, leading to information disclosure.
In multi-tenant Kubernetes clusters, an authenticated namespace-restricted tenant excluded from cross-namespace allowlists can attach operator-owned middlewares from external namespaces to their Service. Red Hat severity: Important — CVSS 7.7 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N).
Weakness: CWE-1220. Red Hat lists Red Hat OpenShift Dev Spaces; Red Hat OpenShift GitOps as not affected.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- Restrict user permissions to modify Service annotations using Kubernetes Admission Controllers or Kyverno policies to prevent unauthorized referencing of traefik.ingress.kubernetes.io/service.middlewares. Alternatively, disable cross-provider namespace resolution in the Traefik Ingress provider configuration until patched.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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