Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-07-24T18:49:48 cluster-proxy: cluster-proxy: Impersonation header injection in service-proxy grants cluster-admin on every managed cluster 8.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H CWE-441

A flaw was found in the cluster-proxy service-proxy component used in Red Hat Advanced Cluster Management for Kubernetes (RHACM) and multicluster-engine (MCE). The service-proxy appends impersonation group headers to proxied requests without first removing caller-supplied values, and the spoke ServiceAccount holds unrestricted impersonation permissions. An authenticated hub principal can inject an Impersonate-Group header to escalate to cluster-admin on every managed cluster.

A flaw was found in the cluster-proxy service-proxy component used in Red Hat Advanced Cluster Management for Kubernetes (RHACM) and multicluster-engine (MCE). The service-proxy appends impersonation group headers to proxied requests without first removing caller-supplied values, and the spoke ServiceAccount holds unrestricted impersonation permissions. An authenticated hub principal can inject an Impersonate-Group header to escalate to cluster-admin on every managed cluster.

A flaw was found in the cluster-proxy service-proxy component of Red Hat Advanced Cluster Management for Kubernetes and multicluster-engine that allows an authenticated hub principal to escalate privileges to cluster-admin across all managed clusters. This is due to improper handling of impersonation group headers, enabling unauthorized administrative access. While the impact of successful exploitation is severe, the attack requires authenticated access to the ACM hub cluster, which is a management-plane component not typically exposed to untrusted networks. Exploitation also depends on knowledge of the cluster-proxy architecture and deliberate construction of requests targeting specific managed clusters. These prerequisites significantly reduce the likelihood of opportunistic or widespread exploitation. Red Hat would like to thank Arpit Jain (GitHub: arpitjain099) and Kahiro Okina (Craftsman Software, Inc.) for reporting this issue. 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. multicluster engine for Kubernetes 2.1 2026-07-27T00:00:00Z RHSA-2026:46885 multicluster-engine/cluster-proxy-rhel9:1784342329 multicluster engine for Kubernetes 2.1 2026-07-28T00:00:00Z RHSA-2026:47388 multicluster-engine/cluster-proxy-rhel9:1784342329 multicluster engine for Kubernetes 2.11 2026-07-29T00:00:00Z RHSA-2026:47974 multicluster-engine/cluster-proxy-rhel9:1784925025 multicluster engine for Kubernetes 2.17 2026-07-29T00:00:00Z RHSA-2026:48284 multicluster-engine/cluster-proxy-rhel9:1784926298 multicluster engine for Kubernetes 2.6 2026-07-29T00:00:00Z RHSA-2026:47949 multicluster-engine/cluster-proxy-rhel9:1783985960 multicluster engine for Kubernetes 2.8 2026-07-29T00:00:00Z RHSA-2026:47735 multicluster-engine/cluster-proxy-rhel9:1784342329 multicluster engine for Kubernetes 2.9 2026-07-29T00:00:00Z RHSA-2026:47953 multicluster-engine/cluster-proxy-rhel9:1783278220 https://www.cve.org/CVERecord?id=CVE-2026-17107 https://nvd.nist.gov/vuln/detail/CVE-2026-17107