Cisco IOS XR Software Malformed TACACS+ Packet Denial of Service Vulnerability

A vulnerability in TACACS+ processing of Cisco IOS XR could allow an unauthenticated, remote attacker to cause a reload of the TACACS+ daemon (tacacsd) on the affected device.

The vulnerability is due to improper parsing of a malformed TACACS+ packet. An attacker could exploit this vulnerability by sending a malformed TACACS+ packet to be processed by an affected device. An exploit could allow the attacker to cause a reload of the TACACS+ process on the device.

Cisco has confirmed the vulnerability in a security notice and released software updates.

To exploit this vulnerability, an attacker may need access to trusted, internal networks behind a firewall to send malformed TACACS+ packets to the targeted device. This access requirement may reduce the likelihood of a successful exploit. In addition, the attacker may need to obtain additional information, such as whether the device has TACACS+ configured, which is a condition that must be met to exploit this vulnerability.

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