CVE-2026-4740

HIGH 8.2

Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal validation

CVSS Score

8.2

EPSS Score

0.0%

EPSS Percentile

0th

A flaw was found in Open Cluster Management (OCM), the technology underlying Red Hat Advanced Cluster Management (ACM). Improper validation of Kubernetes client certificate renewal allows a managed cluster administrator to forge a client certificate that can be approved by the OCM controller. This enables cross-cluster privilege escalation and may allow an attacker to gain control over other managed clusters, including the hub cluster.

CWE	CWE-295
Vendor	red hat
Product	multicluster engine for kubernetes
Published	Apr 7, 2026
Last Updated	Apr 9, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Attack Vector

Local

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

Red Hat / Multicluster Engine for Kubernetes

All versions affected

Red Hat / Multicluster Engine for Kubernetes

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-4740 blog.arfevrier.fr: https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/ bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2450590

Credits

Red Hat would like to thank Arnaud FEVRIER (Orange) for reporting this issue.