CVE-2026-4740Rhacm: open cluster management (ocm): cross-cluster privilege escalation via improper kubernetes client certificate renewal validation
- 8.2HighCVSS base score
- 0.15%Exploitation in 30 daysEPSS · top 96% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By redhat
- 14 days later
· 14 days later
Published
- 5 months later
· 5 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | High8.2 | CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H |
| redhat-SADPADP (enrichment) | 3.1 | High8.2 | CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High8.2 | CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.15% · top 96% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.2.
Affected products
Red Hat · multicluster engine for Kubernetes 2.1
- unaffected 1776881164 – < *
Red Hat · multicluster engine for Kubernetes 2.11
- unaffected 1777478390 – < *
Red Hat · multicluster engine for Kubernetes 2.6
- unaffected 1775977180 – < *
Red Hat · multicluster engine for Kubernetes 2.8
- unaffected 1775638726 – < *
Red Hat · multicluster engine for Kubernetes 2.9
- unaffected 1776445095 – < *
Red Hat · Multicluster Engine for Kubernetes
All versions: unknown
Red Hat · Multicluster Engine for Kubernetes
All versions: unknown
Red Hat · Multicluster Engine for Kubernetes
All versions: unknown
Red Hat · Multicluster Engine for Kubernetes
All versions: unknown
Red Hat · Multicluster Engine for Kubernetes
All versions: unknown
Red Hat · Multicluster Engine for Kubernetes
All versions: unknown
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Goopen-cluster-management.io/ocmGHSA-q4gv-pjmh-c735 (opens in a new tab)
What to do
Workaround: 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.
References
References9
- RHSA-2026:11414 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:13542 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:13853 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:8218 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:9848 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-4740 (opens in a new tab)vdb-entryx_refsource_REDHAT
- https://blog.arfevrier.fr/open-cluster-management-cross-cluster-escape/ (opens in a new tab)
- RHBZ#2450590 (opens in a new tab)issue-trackingx_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4740.json (opens in a new tab)x_sadp-csaf-vex
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-19690 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-q4gv-pjmh-c735 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-4740)Record last updated .