{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-4740", "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "state": "PUBLISHED", "assignerShortName": "redhat", "dateReserved": "2026-03-24T03:19:46.998Z", "datePublished": "2026-04-07T14:30:36.396Z", "dateUpdated": "2026-04-07T14:30:36.396Z"}, "containers": {"cna": {"title": "Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal validation", "metrics": [{"other": {"content": {"value": "Important", "namespace": "https://access.redhat.com/security/updates/classification/"}, "type": "Red Hat severity rating"}}, {"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "HIGH", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "format": "CVSS"}], "descriptions": [{"lang": "en", "value": "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."}], "affected": [{"vendor": "Red Hat", "product": "Multicluster Engine for Kubernetes", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "multicluster-engine/registration-operator-rhel9", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:multicluster_engine"]}, {"vendor": "Red Hat", "product": "Multicluster Engine for Kubernetes", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "multicluster-engine/registration-rhel9", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:multicluster_engine"]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-4740", "tags": ["vdb-entry", "x_refsource_REDHAT"]}, {"url": "https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590", "name": "RHBZ#2450590", "tags": ["issue-tracking", "x_refsource_REDHAT"]}], "datePublic": "2026-04-07T14:00:35.240Z", "problemTypes": [{"descriptions": [{"cweId": "CWE-295", "description": "Improper Certificate Validation", "lang": "en", "type": "CWE"}]}], "x_redhatCweChain": "CWE-295: Improper Certificate Validation", "workarounds": [{"lang": "en", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}], "timeline": [{"lang": "en", "time": "2026-03-24T03:18:24.150Z", "value": "Reported to Red Hat."}, {"lang": "en", "time": "2026-04-07T14:00:35.240Z", "value": "Made public."}], "credits": [{"lang": "en", "value": "Red Hat would like to thank Arnaud FEVRIER (Orange) for reporting this issue."}], "providerMetadata": {"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "shortName": "redhat", "dateUpdated": "2026-04-07T14:30:36.396Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-4740", "lastModified": "2026-04-07T15:17:46.797", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "HIGH", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.5, "impactScore": 6.0, "source": "secalert@redhat.com", "type": "Primary"}]}, "published": "2026-04-07T15:17:46.797", "references": [{"source": "secalert@redhat.com", "url": "https://access.redhat.com/security/cve/CVE-2026-4740"}, {"source": "secalert@redhat.com", "url": "https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/"}, {"source": "secalert@redhat.com", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-295"}], "source": "secalert@redhat.com", "type": "Primary"}]}

{"acknowledgement": "Red Hat would like to thank Arnaud FEVRIER (Orange) for reporting this issue.", "bugzilla": {"description": "rhacm: Open Cluster Management (OCM): Cross-cluster privilege escalation via improper Kubernetes client certificate renewal validation", "id": "2450590", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.2", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-295", "details": ["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."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}, "name": "CVE-2026-4740", "package_state": [{"cpe": "cpe:/a:redhat:multicluster_engine", "fix_state": "Affected", "package_name": "multicluster-engine/registration-operator-rhel9", "product_name": "Multicluster Engine for Kubernetes"}, {"cpe": "cpe:/a:redhat:multicluster_engine", "fix_state": "Affected", "package_name": "multicluster-engine/registration-rhel9", "product_name": "Multicluster Engine for Kubernetes"}], "public_date": "2026-04-07T14:00:35Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-4740\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-4740\nhttps://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/"], "statement": "Improper validation of Kubernetes client certificate renewal in Open Cluster Management (OCM), the technology underlying Red Hat Advanced Cluster Management (ACM), allows a managed cluster administrator to forge a client certificate. This could lead to cross-cluster privilege escalation, potentially enabling an attacker to gain control over other managed clusters, including the hub cluster.", "threat_severity": "Important"}

{}