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Advisory severityHigh8.5Red Hat Linux

High [CVE-2026-17107] Impersonation header injection in service-proxy grants cluster-admin on every managed cluster

This high-severity Red Hat Linux advisory covers CVE-2026-17107 affecting multicluster engine for Kubernetes 2.10, multicluster engine for Kubernetes 2.11.0, multicluster engine for Kubernetes 2.17.

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

CVE-2026-17107 Source published Source updated

VulniPulse record published Record updated

CVE-2026-17107
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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Summary

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. 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 severity: Important — CVSS 8.5 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H).

Weakness: CWE-441. Red Hat fixing advisory: RHSA-2026:46885, RHSA-2026:47388, RHSA-2026:47974, RHSA-2026:48284, RHSA-2026:47949, RHSA-2026:47735, RHSA-2026:47953.

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 16 days ago·verify at source

Fixed versions
  • multicluster-engine/cluster-proxy-rhel9:1784342329
  • multicluster-engine/cluster-proxy-rhel9:1784925025
  • multicluster-engine/cluster-proxy-rhel9:1784926298
  • multicluster-engine/cluster-proxy-rhel9:1783985960
  • multicluster-engine/cluster-proxy-rhel9:1783278220
  • RHSA-2026:46885
  • RHSA-2026:47388
  • RHSA-2026:47974
  • RHSA-2026:48284
  • RHSA-2026:47949
  • RHSA-2026:47735
  • RHSA-2026:47953

Official advisory · high-confidence parse· fetched 16 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 16 days ago·verify at source

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