CVE-2026-4740: Open Cluster Management (OCM) Cross-cluster Privilege Escalation Vulnerability

HIGH
Advisory Identifier: GHSA-q4gv-pjmh-c735
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CVSS 8.2
CWE-295
Published
Advisory Summary

CVE-2026-4740 is a HIGH (CVSS 8.2) cross-cluster privilege escalation vulnerability (CWE-295: Improper Certificate Validation) affecting Open Cluster Management (OCM) libraries in the Go ecosystem. The issue involves cross-cluster privilege escalation via improper kubernetes client certificate renewal validation. Remediation is available by upgrading affected packages to version 1.2.1.

CVE-2026-4740 at a Glance

CVE Identifier CVE-2026-4740
GHSA Identifier GHSA-q4gv-pjmh-c735
Severity HIGH
CVSS v3.1 Base Score 8.2
CWE Classification CWE-295: Improper Certificate Validation
Affected Product Open Cluster Management (OCM)
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 8.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required High (PR:H)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-4740

To remediate this vulnerability, upgrade all affected Open Cluster Management (OCM) dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

open-cluster-management.io/ocm fixed: 1.2.1 
Upgrade open-cluster-management.io/ocm to 1.2.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for open-cluster-management.io/ocm

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-4740, inspect your project dependencies for Open Cluster Management (OCM):

inspect dependencies for open-cluster-management.io/ocm

Analyze the terminal output to locate any version of Open Cluster Management (OCM) in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.2.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-295: Improper Certificate Validation, where the product does not validate, or incorrectly validates, a certificate. In Open Cluster Management (OCM), software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-4740 Affected Open Cluster Management (OCM) Versions

1 component(s)
Fixed Versions:
1.2.1
Product / Package Ecosystem Affected Versions Fixed Version
open-cluster-management.io/ocm
golang/open-cluster-management.io/ocm
Go
< 1.2.1
1.2.1

References

NVD — CVE-2026-4740 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4740
Security Fix Commit FIX COMMIT
https://github.com/open-cluster-management-io/ocm/commit/9e70cc1e21a15239c81111062c0b37df4b5a8026
Open Cluster Management (OCM) Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-4740
blog.arfevrier.fr/open-cluster-manage... WEB
https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2450590
Open Cluster Management (OCM) Source Repository REPOSITORY
https://github.com/open-cluster-management-io/OCM

Frequently Asked Questions

What is CVE-2026-4740?
CVE-2026-4740 is a security vulnerability in Open Cluster Management (OCM) involving Cross-cluster privilege escalation via improper Kubernetes client certificate renewal validation under CWE-295: Improper Certificate Validation.
Which Open Cluster Management (OCM) versions are affected?
Affected versions include releases prior to 1.2.1 across affected packages: open-cluster-management.io/ocm.
What version fixes CVE-2026-4740?
Upgrading to 1.2.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is open-cluster-management.io/ocm affected?
Yes, open-cluster-management.io/ocm is affected in releases prior to 1.2.1. Upgrade your dependency to 1.2.1 or later.
What is the CVSS score of CVE-2026-4740?
CVE-2026-4740 has a CVSS v3.1 base score of 8.2 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-4740?
CVE-2026-4740 is classified under CWE-295: Improper Certificate Validation (The product does not validate, or incorrectly validates, a certificate.).
How can I check Go dependencies for CVE-2026-4740?
Run the dependency tree command: 'inspect dependencies for open-cluster-management.io/ocm'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q4gv-pjmh-c735",
  "modified" : "2026-04-08T19:13:58Z",
  "published" : "2026-04-07T15:30:52Z",
  "aliases" : [ "CVE-2026-4740" ],
  "summary" : "Open Cluster Management (OCM): Cross-cluster privilege escalation via improper Kubernetes client certificate renewal validation",
  "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "open-cluster-management.io/ocm"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.2.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-4740"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-cluster-management-io/ocm/commit/9e70cc1e21a15239c81111062c0b37df4b5a8026"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-4740"
  }, {
    "type" : "WEB",
    "url" : "https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2450590"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-cluster-management-io/OCM"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-295" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-08T19:13:58Z",
    "nvd_published_at" : "2026-04-07T15:17:46Z"
  }
}