Bug 2450590 (CVE-2026-4740)

Summary: CVE-2026-4740 rhacm: Open Cluster Management (OCM): Cross-cluster privilege escalation via improper Kubernetes client certificate renewal validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: alcohan, gparvin, jbalunas, pahickey, rhaigner, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
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.
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-03-24 03:25:48 UTC
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).