CVE-2026-4740 is a high-severity (CVSS 8.2) CWE-295 vulnerability in open-cluster-management.io/ocm. A fix is available for open-cluster-management.io/ocm — see the affected versions and patch details below.
Open Cluster Management (OCM): Cross-cluster privilege escalation via improper Kubernetes client certificate renewal validation
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-4740.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
open-cluster-management.io/ocmReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | open-cluster-management.io/ocm | all versions | 1.2.1go get open-cluster-management.io/ocm@v1.2.1 |
Affected Products
advanced cluster management for kubernetesredhatDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-cluster-management.io/ocm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update open-cluster-management.io/ocm to 1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-4740 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
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…
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.Source: Red Hat security advisory for CVE-2026-4740 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| multicluster engine for Kubernetes 2.1 | multicluster-engine/registration-rhel9:1776881164 | RHSA-2026:13542 |
| multicluster engine for Kubernetes 2.11 | multicluster-engine/registration-rhel9:1777478390 | RHSA-2026:13853 |
| multicluster engine for Kubernetes 2.6 | multicluster-engine/registration-rhel9:1775977180 | RHSA-2026:9848 |
| multicluster engine for Kubernetes 2.8 | multicluster-engine/registration-rhel9:1775638726 | RHSA-2026:8218 |
| multicluster engine for Kubernetes 2.9 | multicluster-engine/registration-rhel9:1776445095 | RHSA-2026:11414 |
Frequently Asked Questions
Is CVE-2026-4740 in your dependencies?
Find it across Go, including transitive dependencies.