Critical [CVE-2026-66794] unauthenticated SSRF to arbitrary managed-cluster services via public Route
This critical-severity Red Hat Linux advisory covers CVE-2026-66794 affecting Multicluster Engine for Kubernetes.
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Summary
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.
Red Hat severity: Important — CVSS 9.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N). Weakness: CWE-918.
Affected Red Hat products: Multicluster Engine for Kubernetes. Red Hat does not currently list a fixing RHSA for this CVE.
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
- To mitigate this issue, restrict network access to the user-facing Route of the `cluster-proxy-addon` to trusted networks only. Implement firewall rules to limit inbound connections to the Route's exposed port, ensuring only authorized sources can reach it. This reduces the attack surface by preventing unauthenticated external access to the vulnerable proxy.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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