Carlos Cortes Alvarez

**Name of the Vulnerable Software and Affected Versions** GNU Inetutils versions 1.9.3 through 2.7 **Description** GNU Inetutils telnetd is vulnerable to a remote authentication bypass. An attacker can exploit this flaw by manipulating the USER environment variable, specifically by setting it to "-f root", to gain unauthorized root access. This vulnerability has been actively exploited and affects systems running telnetd. The flaw has existed for over 11 years and allows attackers to bypass authentication without needing credentials. Approximately 800,000 systems are estimated to be exposed. The vulnerability allows for remote code execution and potential system compromise. **Recommendations** Upgrade to GNU Inetutils version 2.8 or later. If upgrading is not possible, disable the telnetd service entirely. Restrict access to telnetd to trusted IP addresses and monitor logs for suspicious activity.