CRITICAL CVSS 9.8
Published: 2026-01-27

CVE-2020-36941

guelfoweb knockpy Security Advisory (CVE-2020-36941)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2020-36941 impacting guelfoweb knockpy. Evaluated with CVSS Base Score of 9.8 (CRITICAL).

Original NVD Description

Source: NIST NVD
Knockpy 4.1.1 contains a CSV injection vulnerability that allows attackers to inject malicious formulas into CSV reports through unfiltered server headers. Attackers can manipulate server response headers to include spreadsheet formulas that will execute when the CSV is opened in spreadsheet applications.

📊 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
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 guelfoweb / knockpy
Affected Versions 4.1.1
Weakness Enumeration CWE-1236

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-2020-36941 impacting guelfoweb knockpy.

⚡ Nuclei Detection Template (YAML) cve-2020-36941.yaml
id: cve-2020-36941

info:
  name: guelfoweb knockpy - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2020-36941 affecting guelfoweb knockpy.
    Evaluation: Knockpy 4.1.1 contains a CSV injection vulnerability that allows attackers to inject malicious formulas into CSV reports through unfiltered server hea...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2020-36941
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2020-36941
    cwe-id: CWE-1236
  tags: cve,cve-2020-36941,guelfoweb,knockpy,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "knockpy"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2020-36941.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2020-36941
# Target: guelfoweb knockpy | CVSS: 9.8 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2020-36941 (guelfoweb knockpy)...")
    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 guelfoweb knockpy scope (4.1.1).")
        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-2020-36941.sh
# Recommended Remediation & Patching Commands for CVE-2020-36941
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install knockpy 2>/dev/null || \
sudo dnf upgrade knockpy 2>/dev/null || \
sudo yum update knockpy

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

# 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

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2020-36941 in guelfoweb knockpy?

Review vendor-specific security notices and update guelfoweb knockpy 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-2020-36941?

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-2020-36941?

CVE-2020-36941 is classified with a CVSS 3.1 Base Score of 9.8 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.8
CRITICAL SEVERITY
CVE ID CVE-2020-36941
Weakness CWE-1236
Vendor guelfoweb
Product knockpy
Published 2026-01-27
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H