HIGH CVSS 8.2
Published: 2026-04-07

CVE-2026-4740

redhat advanced_cluster_management_for_kubernetes Security Advisory (CVE-2026-4740)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-4740 impacting redhat advanced_cluster_management_for_kubernetes. Evaluated with CVSS Base Score of 8.2 (HIGH).

Original NVD Description

Source: NIST NVD
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.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
High (PR:H)
Administrative credentials required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product redhat / advanced_cluster_management_for_kubernetes
Affected Versions -
Weakness Enumeration CWE-295

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-4740 impacting redhat advanced_cluster_management_for_kubernetes.

⚡ Nuclei Detection Template (YAML) cve-2026-4740.yaml
id: cve-2026-4740

info:
  name: redhat advanced_cluster_management_for_kubernetes - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-4740 affecting redhat advanced_cluster_management_for_kubernetes.
    Evaluation: A flaw was found in Open Cluster Management (OCM), the technology underlying Red Hat Advanced Cluster Management (ACM). Improper validation of Kuberne...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-4740
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 8.2
    cve-id: CVE-2026-4740
    cwe-id: CWE-295
  tags: cve,cve-2026-4740,redhat,advanced_cluster_manageme,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "advanced_cluster_management_for_kubernetes"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-4740.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-4740
# Target: redhat advanced_cluster_management_for_kubernetes | CVSS: 8.2 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-4740 (redhat advanced_cluster_management_for_kubernetes)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against redhat advanced_cluster_management_for_kubernetes scope (-).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-4740.sh
# Recommended Remediation & Patching Commands for CVE-2026-4740
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install advanced_cluster_manageme 2>/dev/null || \
sudo dnf upgrade advanced_cluster_manageme 2>/dev/null || \
sudo yum update advanced_cluster_manageme

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i advanced_cluster_manageme 2>/dev/null || rpm -qa | grep -i advanced_cluster_manageme

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-4740 in redhat advanced_cluster_management_for_kubernetes?

Review vendor-specific security notices and update redhat advanced_cluster_management_for_kubernetes packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-4740?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-4740?

CVE-2026-4740 is classified with a CVSS 3.1 Base Score of 8.2 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
8.2
HIGH SEVERITY
CVE ID CVE-2026-4740
Weakness CWE-295
Vendor redhat
Product advanced_cluster_management_for_kubernetes
Published 2026-04-07
Vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H