UNKNOWN CVSS 5.0
Published: 2009-01-07

CVE-2009-0021

ntp ntp Security Advisory (CVE-2009-0021)
↗ Official NIST NVD Record
Seeking technical exploit breakdowns or verified PoC code for CVE-2009-0021?
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2009-0021 impacting ntp ntp. Evaluated with CVSS Base Score of 5.0 (UNKNOWN).

Original NVD Description

Source: NIST NVD
NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, which allows remote attackers to bypass validation of the certificate chain via a malformed SSL/TLS signature for DSA and ECDSA keys, a similar vulnerability to CVE-2008-5077.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Integrity
None (I:N)
No system modification impact
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product ntp / ntp
Affected Versions *
Weakness Enumeration CWE-287

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-2009-0021 impacting ntp ntp.

⚡ Nuclei Detection Template (YAML) cve-2009-0021.yaml
id: cve-2009-0021

info:
  name: ntp ntp - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: unknown
  description: |
    Automated signature & scanner for CVE-2009-0021 affecting ntp ntp.
    Evaluation: NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, which allows r...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2009-0021
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/Au:N/C:P/I:N/A:N
    cvss-score: 5.0
    cve-id: CVE-2009-0021
    cwe-id: CWE-287
  tags: cve,cve-2009-0021,ntp,ntp,unknown

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "ntp"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2009-0021.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2009-0021
# Target: ntp ntp | CVSS: 5.0 (UNKNOWN)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2009-0021 (ntp ntp)...")
    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 ntp ntp 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-2009-0021.sh
# Recommended Remediation & Patching Commands for CVE-2009-0021
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install ntp 2>/dev/null || \
sudo dnf upgrade ntp 2>/dev/null || \
sudo yum update ntp

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

# 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-2009-0021 in ntp ntp?

Review vendor-specific security notices and update ntp ntp 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-2009-0021?

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-2009-0021?

CVE-2009-0021 is classified with a CVSS 3.1 Base Score of 5.0 (UNKNOWN). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.0
UNKNOWN SEVERITY
CVE ID CVE-2009-0021
Weakness CWE-287
Vendor ntp
Product ntp
Published 2009-01-07
Vector AV:N/AC:L/Au:N/C:P/I:N/A:N