MEDIUM CVSS 5.4
Published: 2021-03-23

CVE-2021-21340

typo3 typo3 Security Advisory (CVE-2021-21340)
↗ Official NIST NVD Record
Seeking technical exploit breakdowns or verified PoC code for CVE-2021-21340?
🔬 Search Writeups & Exploit Archive →

CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2021-21340 impacting typo3 typo3. Evaluated with CVSS Base Score of 5.4 (MEDIUM).

Original NVD Description

Source: NIST NVD
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 10.4.14, 11.1.1 it has been discovered that database fields used as _descriptionColumn_ are vulnerable to cross-site scripting when their content gets previewed. A valid backend user account is needed to exploit this vulnerability. This is fixed in versions 10.4.14, 11.1.1 .

📊 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
Low (PR:L)
Standard user access required
User Interaction
Required (UI:R)
User must click or open resource
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
Low (C:L)
Partial information leakage
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product typo3 / typo3
Affected Versions *
Weakness Enumeration CWE-79

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-2021-21340 impacting typo3 typo3.

⚡ Nuclei Detection Template (YAML) cve-2021-21340.yaml
id: cve-2021-21340

info:
  name: typo3 typo3 - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2021-21340 affecting typo3 typo3.
    Evaluation: TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 10.4.14, 11.1.1 it has been discovered that database fields ...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2021-21340
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 5.4
    cve-id: CVE-2021-21340
    cwe-id: CWE-79
  tags: cve,cve-2021-21340,typo3,typo3,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "typo3"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2021-21340.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2021-21340
# Target: typo3 typo3 | CVSS: 5.4 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2021-21340 (typo3 typo3)...")
    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 typo3 typo3 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-2021-21340.sh
# Recommended Remediation & Patching Commands for CVE-2021-21340
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install typo3 2>/dev/null || \
sudo dnf upgrade typo3 2>/dev/null || \
sudo yum update typo3

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i typo3 2>/dev/null || rpm -qa | grep -i typo3

# 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-2021-21340 in typo3 typo3?

Review vendor-specific security notices and update typo3 typo3 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-2021-21340?

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-2021-21340?

CVE-2021-21340 is classified with a CVSS 3.1 Base Score of 5.4 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.4
MEDIUM SEVERITY
CVE ID CVE-2021-21340
Weakness CWE-79
Vendor typo3
Product typo3
Published 2021-03-23
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N