8.2highHigh
CVE-2026-4740
Redhat Advanced Cluster Management For Kubernetes
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.
Exploitation status
- Published references include exploit or proof-of-concept material. There is no confirmation it is being used in real attacks.
- A vendor advisory or patch reference has been published.
What the metrics mean
- It is requires local access to the machine.
- For an attacker who can reach it, no special conditions are needed to exploit it.
- To exploit it, an administrative account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 8.2 (v3.1)
- Vector
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H- Weakness
- CWE-295
- Assigned by
- secalert@redhat.com
Dates
- Published
- 2026-04-07
- Last modified
- 2026-09-08
- Sources
- NVD
Affected products
- Redhat Advanced Cluster Management For Kubernetesall versions
As listed in the NVD configuration data. Not a statement about your estate.
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
- 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