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Advisory severityCritical9.3Vendor: HighRed Hat Linux

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 2.11, multicluster engine for Kubernetes 2.17, multicluster engine for Kubernetes 2.6.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-66794 Source published Source updated

VulniPulse record published Record updated

CVE-2026-66794
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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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 2.1; multicluster engine for Kubernetes 2.11; multicluster engine for Kubernetes 2.17; multicluster engine for Kubernetes 2.6; multicluster engine for Kubernetes 2.8; multicluster engine for Kubernetes 2.9.

Red Hat fixing advisory: RHSA-2026:59557, RHSA-2026:59556, RHSA-2026:59593, RHSA-2026:59579, RHSA-2026:59558, RHSA-2026:59559.

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 17 days ago·verify at source

Fixed versions
  • multicluster-engine/cluster-proxy-addon-rhel9:1787173361
  • multicluster-engine/cluster-proxy-rhel9:1787276784
  • multicluster-engine/cluster-proxy-rhel9:1786983349
  • multicluster-engine/cluster-proxy-addon-rhel9:1787275318
  • multicluster-engine/cluster-proxy-addon-rhel9:1787275519
  • multicluster-engine/cluster-proxy-addon-rhel9:1787274923
  • RHSA-2026:59557
  • RHSA-2026:59556
  • RHSA-2026:59593
  • RHSA-2026:59579
  • RHSA-2026:59558
  • RHSA-2026:59559

Official advisory · high-confidence parse· fetched 17 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • 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 17 days ago·verify at source

Discussion(0)

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