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Advisory severityCritical9.9Vendor: HighRed Hat Linux

Critical [CVE-2026-66795] CSR auto-approver does not validate certificate Subject or signerName (spoke→hub cluster-admin)

This critical-severity Red Hat Linux advisory covers CVE-2026-66795 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-2026-66795 Source published Source updated

VulniPulse record published Record updated

CVE-2026-66795
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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Summary

A flaw was found in the managedcluster-import-controller. The Certificate Signing Request (CSR) auto-approval logic improperly validates incoming CSRs, specifically by not inspecting the signer name or decoding the PEM-encoded x509 CSR.

This vulnerability allows a privileged service account on a spoke cluster to submit a malicious CSR. Successful exploitation can lead to privilege escalation, enabling the attacker to obtain administrative credentials on the hub cluster.

This poses a significant risk to the overall security of the multicluster environment. Red Hat severity: Important — CVSS 9.9 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).

Weakness: CWE-295. 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 19 days ago·verify at source

Fixed versions
  • multicluster-engine/managedcluster-import-controller-rhel9:1787078272
  • multicluster-engine/managedcluster-import-controller-rhel9:1787078330
  • multicluster-engine/managedcluster-import-controller-rhel9:1786577915
  • multicluster-engine/managedcluster-import-controller-rhel9:1787260779
  • multicluster-engine/managedcluster-import-controller-rhel9:1787259044
  • multicluster-engine/managedcluster-import-controller-rhel9:1787078307
  • RHSA-2026:59557
  • RHSA-2026:59556
  • RHSA-2026:59593
  • RHSA-2026:59579
  • RHSA-2026:59558
  • RHSA-2026:59559

Official advisory · high-confidence parse· fetched 19 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 19 days ago·verify at source

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