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Vulnerability record · CVE-2026-4740 · published 7 April 2026

CVE-2026-4740: Redhat advanced cluster management for kubernetes improper certificate validation vulnerability

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.

8.2 CVSS 3.1 High EPSS 0.16% · top 95.0% CWE-295 · Improper certificate validation
8.2CVSS 3.1 base score
0.16%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
16References, 1 tagged exploit
8 Sep 2026Last modified by NVD

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.

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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 Vendor Advisory
https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/ ExploitThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2450590 Issue TrackingVendor Advisory
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 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2450590 Issue TrackingVendor Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json

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Source: NIST National Vulnerability Database (record CVE-2026-4740), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.