What’s Vulnerable › Vulnerabilities

CVE-2026-4740: Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal validation

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-07 · updated 2026-10-26
• Weakness: CWE-295

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.

Affected products

• Red Hat Advanced Cluster Management for Kubernetes 2: all versions

References

• https://access.redhat.com/errata/RHSA-2026:11414
• https://access.redhat.com/errata/RHSA-2026:13542
• https://access.redhat.com/errata/RHSA-2026:13853
• https://access.redhat.com/errata/RHSA-2026:8218
• https://access.redhat.com/errata/RHSA-2026:9848
• https://access.redhat.com/security/cve/CVE-2026-4740
• https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/
• https://bugzilla.redhat.com/show_bug.cgi?id=2450590
• https://access.redhat.com/errata/RHSA-2026:11414
• https://access.redhat.com/errata/RHSA-2026:13542
• https://access.redhat.com/errata/RHSA-2026:13853
• https://access.redhat.com/errata/RHSA-2026:8218

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