Cisco IOS Voice Gateway Malformed ISDN Q931 Message Denial of Service Vulnerability

A vulnerability in the Integrated Services Digital Network (ISDN) processing code of Cisco IOS could allow an unauthenticated, adjacent attacker to cause a reload of the affected device.

The vulnerability is due to improper processing of malformed ISDN Q931 SETUP messages. An attacker could exploit this vulnerability by sending malformed Q931 SETUP messages to be processed by a targeted device. An exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

Cisco has confirmed the vulnerability and software updates are available.

To exploit this vulnerability, an attacker must be on the same broadcast or collision domain as the targeted device. This access requirement decreases the likelihood of a successful exploit.

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