Cisco Nexus and Cisco Multilayer Director Switches MOTD Telnet Login Reset Vulnerability

A vulnerability in the Message of the Day (MOTD) or banner functionality of the NX-OS Software could allow an unauthenticated, remote attacker to cause the login process to reset.

The vulnerability is due to the MOTD display handling when a certain type of terminal session is requested via Telnet. An attacker could exploit this vulnerability by repeatedly issuing a Telnet session to the NX-OS device, causing the login process to reset. An exploit could allow the attacker to cause the login process of the NX-OS device to reset repeatedly.

Cisco has confirmed the vulnerability; however, software updates are not available.

To exploit this vulnerability, an attacker would need to start a Telnet session with the targeted device. This requirement may decrease the likelihood of a successful exploit depending on how the targeted device is configured.

Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.