CVE-2026-4740

HIGH

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

Title source: cna

Description

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.

References (3)

[Vdb Entry, X_Refsource_Redhat] https://access.redhat.com/security/cve/CVE-2026-4740

[Issue Tracking, X_Refsource_Redhat] https://bugzilla.redhat.com/show_bug.cgi?id=2450590

https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/

Scores

CVSS v3 8.2

EPSS 0.0001

EPSS Percentile 0.8%

Attack Vector LOCAL

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact total

Details

CWE

CWE-295

Status published

Products (3)

open-cluster-management.io/ocm 0 - 1.2.1Go

Red Hat/Multicluster Engine for Kubernetes

redhat/advanced_cluster_management_for_kubernetes

Published Apr 07, 2026

Tracked Since Apr 07, 2026