HIGH CVSS 7.5
Published: 2021-04-08

CVE-2021-1252

clamav clamav Security Advisory (CVE-2021-1252)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2021-1252 impacting clamav clamav. Evaluated with CVSS Base Score of 7.5 (HIGH).

Original NVD Description

Source: NIST NVD
A vulnerability in the Excel XLM macro parsing module in Clam AntiVirus (ClamAV) Software versions 0.103.0 and 0.103.1 could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. The vulnerability is due to improper error handling that may result in an infinite loop. An attacker could exploit this vulnerability by sending a crafted Excel file to an affected device. An exploit could allow the attacker to cause the ClamAV scanning process hang, resulting in a denial of service condition.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product clamav / clamav
Affected Versions 0.103.0
Weakness Enumeration CWE-20

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-2021-1252 impacting clamav clamav.

⚡ Nuclei Detection Template (YAML) cve-2021-1252.yaml
id: cve-2021-1252

info:
  name: clamav clamav - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2021-1252 affecting clamav clamav.
    Evaluation: A vulnerability in the Excel XLM macro parsing module in Clam AntiVirus (ClamAV) Software versions 0.103.0 and 0.103.1 could allow an unauthenticated,...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2021-1252
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    cvss-score: 7.5
    cve-id: CVE-2021-1252
    cwe-id: CWE-20
  tags: cve,cve-2021-1252,clamav,clamav,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "clamav"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2021-1252.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2021-1252
# Target: clamav clamav | CVSS: 7.5 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2021-1252 (clamav clamav)...")
    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 clamav clamav scope (0.103.0).")
        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-2021-1252.sh
# Recommended Remediation & Patching Commands for CVE-2021-1252
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install clamav 2>/dev/null || \
sudo dnf upgrade clamav 2>/dev/null || \
sudo yum update clamav

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

# 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.

🔗 Verified Technical References

Authorities
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2021-1252 in clamav clamav?

Review vendor-specific security notices and update clamav clamav 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-2021-1252?

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-2021-1252?

CVE-2021-1252 is classified with a CVSS 3.1 Base Score of 7.5 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.5
HIGH SEVERITY
CVE ID CVE-2021-1252
Weakness CWE-20
Vendor clamav
Product clamav
Published 2021-04-08
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H