CVE-2026-4740: Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal validation
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.
Other sources
Improper validation of Kubernetes client certificate renewal in Open Cluster Management (OCM), the technology underlying Red Hat Advanced Cluster Management (ACM), allows a managed cluster administrator to forge a client certificate that can be approved by the OCM controller.
Due to predictable cluster name prefix matching, this enables cross-cluster privilege escalation and may allow an attacker to gain control over other managed clusters (including the hub cluster).
— Red Hat