CVE-2026-4740Public exploit

Cross-cluster privilege escalation via forged certificate renewal

Published Apr 7, 2026 · Updated Aug 25, 2026

Improper certificate validation in Open Cluster Management before 1.2.1 allows local users to gain cross-cluster access via forged CSR renewals. In pkg/registration/register/csr/approve_reconciler.go, the renewal approver accepted cluster identity by prefix and user-controlled label data instead of requiring an exact match among the CSR Common Name, organization, and managed-cluster label. Exploitation requires administrator-level control of one managed cluster, after which a forged certificate can patch ManifestWork for another cluster and can reach the hub cluster when names satisfy the exploitable prefix relationship.

CVSS severity8.2
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Open Cluster Management before 1.2.1 allows local users to gain cross-cluster access via forged CSR renewals. In pkg/registration/register/csr/approve_reconciler.go, the renewal approver accepted cluster identity by prefix and user-controlled label data instead of requiring an exact match among the CSR Common Name, organization, and managed-cluster label. Exploitation requires administrator-level control of one managed cluster, after which a forged certificate can patch ManifestWork for another cluster and can reach the hub cluster when names satisfy the exploitable prefix relationship.

The record

CVE
CVE-2026-4740
Published
Apr 7, 2026
Updated
Aug 25, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-295, T1550
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.2Red HatCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1550Use Alternate Authentication Material

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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