CVE-2026-66794: Cluster-proxy-addon: cluster-proxy-addon: unauthenticated ssrf to arbitrary managed-cluster services via public route

Severity: critical (CVSS 9.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-19 · updated 2026-10-26
Weakness: CWE-918

Description

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: all versions — fixed in 1787173361
Red Hat multicluster engine for Kubernetes 2.11: all versions — fixed in 1787276784
Red Hat multicluster engine for Kubernetes 2.17: all versions — fixed in 1786983349
Red Hat multicluster engine for Kubernetes 2.6: all versions — fixed in 1787275318
Red Hat multicluster engine for Kubernetes 2.8: all versions — fixed in 1787275519
Red Hat multicluster engine for Kubernetes 2.9: all versions — fixed in 1787274923

How to fix

Upgrade to a fixed version: Red Hat multicluster engine for Kubernetes 2.10 1787173361; Red Hat multicluster engine for Kubernetes 2.11 1787276784; Red Hat multicluster engine for Kubernetes 2.17 1786983349; Red Hat multicluster engine for Kubernetes 2.6 1787275318; Red Hat multicluster engine for Kubernetes 2.8 1787275519; Red Hat multicluster engine for Kubernetes 2.9 1787274923. Check the vendor advisory for mitigations.

References

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