CVE-2026-4740
Medium
Elevated severity or exploit probability.
CVSS base
8.2
HIGH
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS — probability of exploitation (30 days)
0.2%
4.9th percentile
CISA KEV
Not listed
Weakness / dates
CWE-295
Published 2026-04-07 · modified 2026-09-08
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
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
- exploit 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
- https://access.redhat.com/errata/RHSA-2026:9848
- https://access.redhat.com/security/cve/CVE-2026-4740
- https://bugzilla.redhat.com/show_bug.cgi?id=2450590
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json