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    CVE-2026-4740

    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.

    Published:Apr 7, 2026
    Last Modified:Aug 12, 2026
    EPS:Apr 7, 2026
    EPSS Score:0.00112
    CVSS Score:8.2

    Affected Products

    Vendor
    Redhat
    Product
    Advanced Cluster Management For Kubernetes
    Vendor
    Redhat
    Product
    Multicluster Engine

    Exploits

    https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/

    Common Weakness Enumeration

    CWE-295 Improper Certificate Validation

    Related CVEs

    CVE-2026-73137 (CVSS 7.7) — A flaw was found in the multicloud-operators-subscription component of Red Hat Advanced Cluster Management (RH…
    CVE-2026-67567 (CVSS 9.9) — A flaw was found in the multicloud-operators-subscription component. This vulnerability allows a tenant, who h…
    CVE-2026-66785 (CVSS 2.5) — A flaw was found in Submariner. This vulnerability allows a malicious cluster (spoke) to redirect network traf…
    CVE-2026-66787 (CVSS 5.4) — A flaw was found in the lighthouse component of Red Hat Advanced Cluster Management for Kubernetes. This vulne…
    CVE-2026-66788 (CVSS 3.7) — A flaw was found in Lighthouse. A remote attacker, by compromising a spoke cluster, can exploit a vulnerabilit…
    CVE-2026-76827 (CVSS 6.8) — A flaw was found in search-indexer. This vulnerability allows a registered and authenticated managed cluster t…
    CVE-2026-76139 (CVSS 8) — A flaw was found in acm-operator-bundle. The build process for this component downloads and runs a script from…
    CVE-2026-18874 (CVSS 6.2) — A flaw was found in volsync-addon-controller. This vulnerability allows an attacker to inject malicious YAML (…
    CVE-2026-71470 (CVSS 9.1) — A flaw was found in the search-v2-operator. This vulnerability allows a privileged user, specifically a Custom…
    CVE-2026-70496 (CVSS 9.9) — A flaw was found in search-v2-operator. The operator's ClusterRole has permissions equivalent to a cluster adm…

    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
    https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High