Critical Vulnerability in GNU Inetutils Telnet Daemon

Security researchers at Dream Security Labs have disclosed a critical vulnerability in the GNU Inetutils telnet daemon that allows unauthenticated attackers to execute arbitrary code on affected systems, potentially granting root-level access before any login process begins. The flaw, tracked as CVE-2026-32746 and assigned a CVSS 3.1 severity score of 9.8, stems from a buffer overflow in the daemon's handling of the LINEMODE Set Local Characters option during initial Telnet protocol negotiations. It affects all versions of GNU Inetutils up to and including 2.7 and was publicly detailed in an advisory released on March 13, 2026, following responsible disclosure to the project's maintainers.

The vulnerability arises when an attacker connects to a system's TCP port 23, the standard Telnet port, and sends a specially crafted suboption message containing an excessive number of data triplets. This triggers an out-of-bounds write in a fixed-size buffer, corrupting adjacent memory without any bounds checking. As telnetd often operates with root privileges through services like inetd or xinetd, successful exploitation can lead to full system compromise, including the installation of...