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Advisory severityHigh7.1Red Hat Linux

High [CVE-2026-73266] tenant-controlled ClusterClaim labels propagated to ManagedCluster enabling cross-tenant ManagedClusterSet join

This high-severity Red Hat Linux advisory covers CVE-2026-73266 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-2026-73266 Source published Source updated

VulniPulse record published Record updated

CVE-2026-73266
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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Summary

A flaw was found in the clusterclaims-controller component of Multicluster Engine (MCE). An authenticated tenant can exploit this vulnerability by manipulating ClusterClaim labels.

This allows the tenant to force a cluster to join a ManagedClusterSet belonging to another tenant. Such unauthorized access could enable the injection of policies and workloads into other tenants' clusters.

This Important flaw in Multicluster Engine for Kubernetes' clusterclaims-controller allows a tenant to propagate arbitrary labels from a ClusterClaim to a ManagedCluster object. This enables unauthorized cross-tenant ManagedClusterSet joins, leading to policy and workload injection into victim clusters.

The vulnerability breaks tenant isolation, granting an attacker control over resources belonging to other tenants. Red Hat severity: Important — CVSS 7.1 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N).

Weakness: CWE-441. 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 28 days ago·verify at source

Fixed versions
  • multicluster-engine/clusterclaims-controller-rhel9:1787196014
  • multicluster-engine/clusterclaims-controller-rhel9:1787239442
  • multicluster-engine/clusterclaims-controller-rhel9:1786577950
  • multicluster-engine/clusterclaims-controller-rhel9:1787259112
  • multicluster-engine/clusterclaims-controller-rhel9:1787259059
  • multicluster-engine/clusterclaims-controller-rhel9:1787195995
  • RHSA-2026:59557
  • RHSA-2026:59556
  • RHSA-2026:59593
  • RHSA-2026:59579
  • RHSA-2026:59558
  • RHSA-2026:59559

Official advisory · high-confidence parse· fetched 28 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Official advisory · high-confidence parse· fetched 28 days ago·verify at source

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