CVE-2026-66794: Red Hat Multicluster Engine For Kubernetes 2.10

Critical severity, CVSS 9.3. EPSS: 0.6% chance of exploitation in the next 30 days.

A flaw was found in the `cluster-proxy-addon` component of Multicluster Engine for Kubernetes. This vulnerability allows an unauthenticated attacker, who can access the user-facing route, to bypass authentication and authorization checks. By manipulating URL path segments, the attacker can proxy requests to arbitrary services across any managed cluster. This enables unauthorized access to internal services that would otherwise be protected, potentially leading to information disclosure or further compromise of the cluster environment.

Affected products

• Red Hat Multicluster Engine For Kubernetes 2.10: before 1787173361 (fixed in 1787173361)
• Red Hat Multicluster Engine For Kubernetes 2.11: before 1787276784 (fixed in 1787276784)
• Red Hat Multicluster Engine For Kubernetes 2.17: before 1786983349 (fixed in 1786983349)
• Red Hat Multicluster Engine For Kubernetes 2.6: before 1787275318 (fixed in 1787275318)
• Red Hat Multicluster Engine For Kubernetes 2.8: before 1787275519 (fixed in 1787275519)
• Red Hat Multicluster Engine For Kubernetes 2.9: before 1787274923 (fixed in 1787274923)

Published 2026-08-19. Last modified 2026-09-29.