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

Quick assessment

Affected
Red Hat multicluster engine for Kubernetes 2.1
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Red Hat rhacm2是美国红帽（Red Hat）公司的一个库。 Red Hat rhacm2存在信任管理问题漏洞，该漏洞源于Kubernetes客户端证书续订验证不当，可能导致受管集群管理员伪造可被OCM控制器批准的客户端证书，从而实现跨集群权限提升并控制其他受管集群。

CVSS 8.2 · High EPSS 0.16% · P5

Affected Version Matrix 11

VendorProduct Version RangeStatus
Red Hat Multicluster Engine for Kubernetes any unknown
any unknown
any unknown
any unknown
any unknown
any unknown
Red Hat multicluster engine for Kubernetes 2.1 1776881164< * unaffected
Red Hat multicluster engine for Kubernetes 2.11 1777478390< * unaffected
Red Hat multicluster engine for Kubernetes 2.6 1775977180< * unaffected
Red Hat multicluster engine for Kubernetes 2.8 1775638726< * unaffected
Red Hat multicluster engine for Kubernetes 2.9 1776445095< * unaffected
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I. Basic Information for CVE-2026-4740

Vulnerability Information
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Vulnerability Title
Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal validation
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
证书验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Red Hat rhacm2 信任管理问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Red Hat rhacm2是美国红帽（Red Hat）公司的一个库。 Red Hat rhacm2存在信任管理问题漏洞，该漏洞源于Kubernetes客户端证书续订验证不当，可能导致受管集群管理员伪造可被OCM控制器批准的客户端证书，从而实现跨集群权限提升并控制其他受管集群。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat multicluster engine for Kubernetes 2.1 1776881164 ~ * cpe:/a:redhat:multicluster_engine:2.10::el9
Red Hat multicluster engine for Kubernetes 2.11 1777478390 ~ * cpe:/a:redhat:multicluster_engine:2.11::el9
Red Hat multicluster engine for Kubernetes 2.6 1775977180 ~ * cpe:/a:redhat:multicluster_engine:2.6::el9
Red Hat multicluster engine for Kubernetes 2.8 1775638726 ~ * cpe:/a:redhat:multicluster_engine:2.8::el9
Red Hat multicluster engine for Kubernetes 2.9 1776445095 ~ * cpe:/a:redhat:multicluster_engine:2.9::el9
Red Hat Multicluster Engine for Kubernetes - cpe:/a:redhat:multicluster_engine
Red Hat Multicluster Engine for Kubernetes - cpe:/a:redhat:multicluster_engine
Red Hat Multicluster Engine for Kubernetes - cpe:/a:redhat:multicluster_engine
Red Hat Multicluster Engine for Kubernetes - cpe:/a:redhat:multicluster_engine
Red Hat Multicluster Engine for Kubernetes - cpe:/a:redhat:multicluster_engine
Red Hat Multicluster Engine for Kubernetes - cpe:/a:redhat:multicluster_engine

II. Public POCs for CVE-2026-4740

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III. Intelligence Information for CVE-2026-4740

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Vendor Advisories for CVE-2026-4740 (7)

Same Patch Batch · Red Hat · 2026-04-07 · 4 CVEs total

CVE-2026-4631 9.8 CRITICAL Cockpit: cockpit: unauthenticated remote code execution due to ssh command-line argument i
CVE-2025-14821 7.8 HIGH Libssh: libssh: insecure default configuration leads to local man-in-the-middle attacks on
CVE-2026-5745 5.5 MEDIUM Libarchive: a null pointer dereference vulnerability exists in the acl parser of libarchiv

IV. Related Vulnerabilities

Same product: multicluster engine for Kubernetes 2.1
Same vendor: Red Hat
Same weakness: CWE-295

V. Comments for CVE-2026-4740

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