NVD

CVE-2026-4740 Detail

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.

Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

CVSS 3.x Severity and Vector Strings:

Nist CVSS score does not match with CNA score

CNA: Red Hat, Inc.

Base Score: 8.2 HIGH

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

CVSS 2.0 Severity and Vector Strings:

National Institute of Standards and Technology

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://access.redhat.com/security/cve/CVE-2026-4740	Red Hat, Inc.	Vendor Advisory
https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/	Red Hat, Inc.	Exploit Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2450590	Red Hat, Inc.	Issue Tracking Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-295	Improper Certificate Validation	Red Hat, Inc.

Known Affected Software Configurations Switch to CPE 2.2

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Change History

4 change records found show changes

CVE Modified by Red Hat, Inc. 6/17/2026 6:57:09 AM

Action

Type

Old Value

New Value

Added

Affected

[{"vendor":"Red Hat","product":"Multicluster Engine for Kubernetes","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"multicluster-engine/addon-manager-rhel9","cpes":["cpe:/a:redhat:multicluster_engine"]},{"vendor":"Red Hat","product":"Multicluster Engine for Kubernetes","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"multicluster-engine/managedcluster-import-controller-rhel9","cpes":["cpe:/a:redhat:multicluster_engine"]},{"vendor":"Red Hat","product":"Multicluster Engine for Kubernetes","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"multicluster-engine/placement-rhel9","cpes":["cpe:/a:redhat:multicluster_engine"]},{"vendor":"Red Hat","product":"Multicluster Engine for Kubernetes","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"multicluster-engine/registration-operator-rhel9","cpes":["cpe:/a:redhat:multicluster_engine"]},{"vendor":"Red Hat","product":"Multicluster Engine for Kubernetes","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"multicluster-engine/registration-rhel9","cpes":["cpe:/a:redhat:multicluster_engine"]},{"vendor":"Red Hat","product":"Multicluster Engine for Kubernetes","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"multicluster-engine/work-rhel9","cpes":["cpe:/a:redhat:multicluster_engine"]}]

Initial Analysis by NIST 4/28/2026 4:39:15 PM

Action	Type	New Value
Added	CPE Configuration	OR cpe:2.3:a:redhat:advanced_cluster_management_for_kubernetes:-:::::::
Added	Reference Type	Red Hat, Inc.: https://access.redhat.com/security/cve/CVE-2026-4740 Types: Vendor Advisory
Added	Reference Type	Red Hat, Inc.: https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/ Types: Exploit, Third Party Advisory
Added	Reference Type	Red Hat, Inc.: https://bugzilla.redhat.com/show_bug.cgi?id=2450590 Types: Issue Tracking, Vendor Advisory

New CVE Received from Red Hat, Inc. 4/07/2026 11:17:46 AM

Action	Type	New Value
Added	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.
Added	CVSS V3.1	AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Added	CWE	CWE-295
Added	Reference	https://access.redhat.com/security/cve/CVE-2026-4740
Added	Reference	https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/
Added	Reference	https://bugzilla.redhat.com/show_bug.cgi?id=2450590

Quick Info

CVE Dictionary Entry:
CVE-2026-4740
NVD Published Date:
04/07/2026
NVD Last Modified:
06/17/2026
Source:
Red Hat, Inc.

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Information Technology Laboratory

National Vulnerability Database