{"id":"CVE-2026-4740","title":"A flaw was found in Open Cluster Management (OCM), the technology underlying Red Hat Advanced Cluster Management (ACM)","summary":"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…","severity":"high","cvss":8.2,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H","cwe":["CWE-295"],"vendor":"redhat","product":"advanced_cluster_management_for_kubernetes","affected":["advanced_cluster_management_for_kubernetes"],"published":"2026-04-07","updated":"2026-09-08","sourceUpdated":"2026-09-08T12:16:54.783","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-4740","references":[{"url":"https://access.redhat.com/errata/RHSA-2026:11414","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:13542","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:13853","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:8218","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:9848","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/security/cve/CVE-2026-4740","label":"secalert@redhat.com"},{"url":"https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2450590","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:11414","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:13542","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:13853","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:8218","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:9848","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/security/cve/CVE-2026-4740","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2450590","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-4740"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-4740"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-04-09T14:40:37.454585Z"},"epss":0.00148,"epssPercentile":0.04419,"ingestedAt":"2026-07-13T17:27:58.720Z","patched":["multicluster_engine_for_kubernetes 2.11","multicluster_engine_for_kubernetes 2.1","multicluster_engine_for_kubernetes 2.6","multicluster_engine_for_kubernetes 2.8","multicluster_engine_for_kubernetes 2.9"],"slug":"CVE-2026-4740","body":"## Overview\n\nA 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.\n\n## Affected\n\n- `advanced_cluster_management_for_kubernetes`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:13853** · Red Hat · fixed in: multicluster engine for Kubernetes 2.11 · released 2026-05-05 · [advisory](https://access.redhat.com/errata/RHSA-2026:13853)\n- **RHSA-2026:13542** · Red Hat · fixed in: multicluster engine for Kubernetes 2.1 · released 2026-05-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:13542)\n- **RHSA-2026:9848** · Red Hat · fixed in: multicluster engine for Kubernetes 2.6 · released 2026-04-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:9848)\n- **RHSA-2026:8218** · Red Hat · fixed in: multicluster engine for Kubernetes 2.8 · released 2026-04-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:8218)\n- **RHSA-2026:11414** · Red Hat · fixed in: multicluster engine for Kubernetes 2.9 · released 2026-04-28 · [advisory](https://access.redhat.com/errata/RHSA-2026:11414)\n- **Red Hat VEX** · Important · affected: Multicluster Engine for Kubernetes · updated 2026-09-08 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json)","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}