Cisco IOS XR Software DHCPv4 Server Denial of Service Vulnerability

A vulnerability in the DHCP process of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

The vulnerability is due to improper processing of crafted DHCP messages on a targeted interface of an affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending large amounts of crafted DHCP messages to a targeted interface on an affected device. A successful exploit could cause the device to stop responding to DHCP requests on that interface, resulting in a DoS condition.

Cisco has confirmed the vulnerability and released software updates.

To exploit this vulnerability, an attacker may need access to trusted, internal networks behind a firewall to send large amounts of crafted DHCP messages to an interface on the device. This access requirement may reduce 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.