Vulnerability-Lookup

FKIE_CVE-2026-4740

Vulnerability from fkie_nvd - Published: 2026-04-07 15:17 - Updated: 2026-09-08 12:16

Severity

8.2 (High) - CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
8.2 (High) - CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

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 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.

References

URL	Tags
secalert@redhat.com	https://access.redhat.com/errata/RHSA-2026:11414
secalert@redhat.com	https://access.redhat.com/errata/RHSA-2026:13542
secalert@redhat.com	https://access.redhat.com/errata/RHSA-2026:13853
secalert@redhat.com	https://access.redhat.com/errata/RHSA-2026:8218
secalert@redhat.com	https://access.redhat.com/errata/RHSA-2026:9848
secalert@redhat.com	https://access.redhat.com/security/cve/CVE-2026-4740	Vendor Advisory
secalert@redhat.com	https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/	Exploit, Third Party Advisory
secalert@redhat.com	https://bugzilla.redhat.com/show_bug.cgi?id=2450590	Issue Tracking, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:11414
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:13542
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:13853
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:8218
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:9848
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/security/cve/CVE-2026-4740	Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://bugzilla.redhat.com/show_bug.cgi?id=2450590	Issue Tracking, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json

Impacted products

	Vendor	Product	Version
	redhat	advanced_cluster_management_for_kubernetes	-

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.10::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.1",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1776881164",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.11::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.11",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1777478390",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.6::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.6",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1775977180",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.8::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.8",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1775638726",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.9::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.9",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1776445095",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/addon-manager-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/maestro-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/managedcluster-import-controller-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/placement-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/registration-operator-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/work-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        }
      ],
      "source": "secalert@redhat.com"
    },
    {
      "affectedData": [
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.10::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.1",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1776881164",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.11::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.11",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1777478390",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.6::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.6",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1775977180",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.8::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.8",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1775638726",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.9::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.9",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1776445095",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/addon-manager-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/maestro-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/managedcluster-import-controller-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/placement-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/registration-operator-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/work-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        }
      ],
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:redhat:advanced_cluster_management_for_kubernetes:-:*:*:*:*:*:*:*",
              "matchCriteriaId": "7301AD20-0188-463F-9386-9D878AD3A542",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "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": "2026-09-08T12:16:54.783",
  "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": "Secondary"
      },
      {
        "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": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-4740",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-09T14:40:37.454585Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-07T15:17:46.797",
  "references": [
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/errata/RHSA-2026:11414"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/errata/RHSA-2026:13542"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/errata/RHSA-2026:13853"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/errata/RHSA-2026:8218"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/errata/RHSA-2026:9848"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://access.redhat.com/security/cve/CVE-2026-4740"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "url": "https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:11414"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:13542"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:13853"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:8218"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/errata/RHSA-2026:9848"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://access.redhat.com/security/cve/CVE-2026-4740"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "tags": [
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json"
    }
  ],
  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        }
      ],
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "type": "Secondary"
    }
  ]
}

CVE-2026-4740 (GCVE-0-2026-4740)

Vulnerability from cvelistv5 – Published: 2026-04-07 14:30 – Updated: 2026-09-09 12:04

Title

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

Summary

Severity

8.2 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-09 14:40 UTC

CWE

CWE-295 - Improper Certificate Validation

Assigner

redhat redhat root

References

9 references

URL	Tags
https://access.redhat.com/errata/RHSA-2026:11414	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:13542	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:13853	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:8218	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:9848	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-4740	vdb-entryx_refsource_REDHAT
https://blog.arfevrier.fr/open-cluster-management…
https://bugzilla.redhat.com/show_bug.cgi?id=2450590	issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v…	x_sadp-csaf-vex

Impacted products

6 products

Vendor	Product	Version
Red Hat	multicluster engine for Kubernetes 2.1	Unaffected: 1776881164 , < * (rpm) cpe:/a:redhat:multicluster_engine:2.10::el9
Red Hat	multicluster engine for Kubernetes 2.11	Unaffected: 1777478390 , < * (rpm) cpe:/a:redhat:multicluster_engine:2.11::el9
Red Hat	multicluster engine for Kubernetes 2.6	Unaffected: 1775977180 , < * (rpm) cpe:/a:redhat:multicluster_engine:2.6::el9
Red Hat	multicluster engine for Kubernetes 2.8	Unaffected: 1775638726 , < * (rpm) cpe:/a:redhat:multicluster_engine:2.8::el9
Red Hat	multicluster engine for Kubernetes 2.9	Unaffected: 1776445095 , < * (rpm) cpe:/a:redhat:multicluster_engine:2.9::el9
Red Hat	Multicluster Engine for Kubernetes	cpe:/a:redhat:multicluster_engine

Date Public

2026-04-07 14:00

Credits

Red Hat would like to thank Arnaud FEVRIER (Orange) for reporting this issue.

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-4740",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-09T14:40:37.454585Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-09T14:40:43.580Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "affected": [
          {
            "collectionURL": "https://catalog.redhat.com/software/containers/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine:2.10::el9"
            ],
            "defaultStatus": "affected",
            "packageName": "multicluster-engine/registration-rhel9",
            "product": "multicluster engine for Kubernetes 2.1",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "1776881164",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://catalog.redhat.com/software/containers/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine:2.11::el9"
            ],
            "defaultStatus": "affected",
            "packageName": "multicluster-engine/registration-rhel9",
            "product": "multicluster engine for Kubernetes 2.11",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "1777478390",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://catalog.redhat.com/software/containers/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine:2.6::el9"
            ],
            "defaultStatus": "affected",
            "packageName": "multicluster-engine/registration-rhel9",
            "product": "multicluster engine for Kubernetes 2.6",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "1775977180",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://catalog.redhat.com/software/containers/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine:2.8::el9"
            ],
            "defaultStatus": "affected",
            "packageName": "multicluster-engine/registration-rhel9",
            "product": "multicluster engine for Kubernetes 2.8",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "1775638726",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://catalog.redhat.com/software/containers/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine:2.9::el9"
            ],
            "defaultStatus": "affected",
            "packageName": "multicluster-engine/registration-rhel9",
            "product": "multicluster engine for Kubernetes 2.9",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "1776445095",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine"
            ],
            "defaultStatus": "unknown",
            "packageName": "multicluster-engine/addon-manager-rhel9",
            "product": "Multicluster Engine for Kubernetes",
            "vendor": "Red Hat"
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine"
            ],
            "defaultStatus": "unknown",
            "packageName": "multicluster-engine/maestro-rhel9",
            "product": "Multicluster Engine for Kubernetes",
            "vendor": "Red Hat"
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine"
            ],
            "defaultStatus": "unknown",
            "packageName": "multicluster-engine/managedcluster-import-controller-rhel9",
            "product": "Multicluster Engine for Kubernetes",
            "vendor": "Red Hat"
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine"
            ],
            "defaultStatus": "unknown",
            "packageName": "multicluster-engine/placement-rhel9",
            "product": "Multicluster Engine for Kubernetes",
            "vendor": "Red Hat"
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine"
            ],
            "defaultStatus": "unknown",
            "packageName": "multicluster-engine/registration-operator-rhel9",
            "product": "Multicluster Engine for Kubernetes",
            "vendor": "Red Hat"
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:multicluster_engine"
            ],
            "defaultStatus": "unknown",
            "packageName": "multicluster-engine/work-rhel9",
            "product": "Multicluster Engine for Kubernetes",
            "vendor": "Red Hat"
          }
        ],
        "datePublic": "2026-04-07T14:00:35.240Z",
        "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."
          }
        ],
        "metrics": [
          {
            "other": {
              "content": {
                "namespace": "https://access.redhat.com/security/updates/classification/",
                "value": "Important"
              },
              "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"
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-295",
                "description": "Improper Certificate Validation",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-09T12:04:44.287Z",
          "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
          "shortName": "redhat-SADP"
        },
        "references": [
          {
            "tags": [
              "vdb-entry",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2026-4740"
          },
          {
            "name": "RHBZ#2450590",
            "tags": [
              "issue-tracking",
              "x_refsource_REDHAT"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"
          },
          {
            "tags": [
              "x_sadp-csaf-vex"
            ],
            "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:13853"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:13542"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:9848"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:8218"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:11414"
          }
        ],
        "solutions": [
          {
            "lang": "en",
            "value": "RHSA-2026:13853: multicluster engine for Kubernetes 2.11"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:13542: multicluster engine for Kubernetes 2.1"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:9848: multicluster engine for Kubernetes 2.6"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:8218: multicluster engine for Kubernetes 2.8"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:11414: multicluster engine for Kubernetes 2.9"
          }
        ],
        "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."
          }
        ],
        "title": "rhacm: Open Cluster Management (OCM): Cross-cluster privilege escalation via improper Kubernetes client certificate renewal 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."
          }
        ],
        "x_adpType": "supplier",
        "x_generator": {
          "engine": "sadp-cli 1.0.0"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.10::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.1",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1776881164",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.11::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.11",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1777478390",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.6::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.6",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1775977180",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.8::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.8",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1775638726",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine:2.9::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "multicluster-engine/registration-rhel9",
          "product": "multicluster engine for Kubernetes 2.9",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "1776445095",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/addon-manager-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/maestro-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/managedcluster-import-controller-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/placement-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/registration-operator-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:multicluster_engine"
          ],
          "defaultStatus": "unknown",
          "packageName": "multicluster-engine/work-rhel9",
          "product": "Multicluster Engine for Kubernetes",
          "vendor": "Red Hat"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Red Hat would like to thank Arnaud FEVRIER (Orange) for reporting this issue."
        }
      ],
      "datePublic": "2026-04-07T14:00:35.240Z",
      "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."
        }
      ],
      "metrics": [
        {
          "other": {
            "content": {
              "namespace": "https://access.redhat.com/security/updates/classification/",
              "value": "Important"
            },
            "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"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-08T11:38:18.133Z",
        "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "shortName": "redhat"
      },
      "references": [
        {
          "name": "RHSA-2026:11414",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:11414"
        },
        {
          "name": "RHSA-2026:13542",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:13542"
        },
        {
          "name": "RHSA-2026:13853",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:13853"
        },
        {
          "name": "RHSA-2026:8218",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:8218"
        },
        {
          "name": "RHSA-2026:9848",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:9848"
        },
        {
          "tags": [
            "vdb-entry",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/security/cve/CVE-2026-4740"
        },
        {
          "url": "https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/"
        },
        {
          "name": "RHBZ#2450590",
          "tags": [
            "issue-tracking",
            "x_refsource_REDHAT"
          ],
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"
        }
      ],
      "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."
        }
      ],
      "title": "Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal 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."
        }
      ],
      "x_generator": {
        "engine": "cvelib 1.8.0"
      },
      "x_redhatCweChain": "CWE-295: Improper Certificate Validation"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
    "assignerShortName": "redhat",
    "cveId": "CVE-2026-4740",
    "datePublished": "2026-04-07T14:30:36.396Z",
    "dateReserved": "2026-03-24T03:19:46.998Z",
    "dateUpdated": "2026-09-09T12:04:44.287Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

FKIE_CVE-2026-4740

CVE-2026-4740 (GCVE-0-2026-4740)

Tags

Sightings

Nomenclature

Related by attack behaviour