TelnetdBypass — CVE-2026-24061 Scanner

A Python-based security scanner that detects and exploits CVE-2026-24061, a critical (CVSS 9.8) authentication bypass vulnerability in GNU InetUtils telnetd versions 1.9.3 through 2.7.

How it Works

The scanner injects a malicious USER=-f root value via the Telnet NEW-ENVIRON option (RFC 1572), tricking the server into skipping authentication and granting a root shell.

Features

• Single IP, hostname, or full CIDR range scanning
• Multi-threaded (default 50 threads) for fast results
• Live progress bar with coloured terminal output
• Post-exploitation confirmation via id command
• Saves reports in plain text or JSON format

Usage

# Scan single target
sudo python3 telnetd_scanner.py -t 192.168.56.101 -p 23 -v

# Scan entire subnet
sudo python3 telnetd_scanner.py -t 192.168.56.0/24 --threads 30

# Save report
sudo python3 telnetd_scanner.py -t 192.168.56.101 -o report.txt

# JSON output
sudo python3 telnetd_scanner.py -t 192.168.56.101 --format json -o report.json

Affected Versions

Tested On

• Kali Linux (attacker)
• Debian 11 with inetutils-telnetd (target)
• VirtualBox Host-Only Network

Disclaimer

This tool is for authorised security research and educational purposes only. Do not use against systems you do not own or have explicit permission to test.

Author

Ahmad Sadeeq