Cisco IOS XR Software NetFlow Processing Denial of Service Vulnerability

A vulnerability in NetFlow processing in Cisco IOS XR Software for ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, adjacent attacker to cause a lockup and eventual reload of a Network Processor (NP) chip and a line card processing traffic.

The vulnerability is due to improper NetFlow sampling of malformed IP version 4 (IPv4) or IP version 6 (IPv6) packets. An attacker could exploit this vulnerability by sending a stream of malformed IPv4 or IPv6 packets to be processed through an affected device. An exploit could allow the attacker to cause a lockup and eventual reload of an NP chip and a line card, leading to a denial of service (DoS) condition.

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

To exploit this vulnerability, an attacker must be on the same broadcast or collision domain as the targeted device to send a stream of malformed IPv4 or IPv6 packets to the device. This access requirement may reduce the likelihood of a successful exploit.

For an attacker to exploit this vulnerability, NetFlow sampling must be configured on the targeted device.

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