Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers Denial of Service Vulnerability

A vulnerability in flow control processing of Cisco IOS XR Software for Cisco ASR 9000 Series Routers could allow an unauthenticated, adjacent attacker to cause a Network Processing Unit (NPU) chip reset and potentially a reload of the affected line card.

The vulnerability is due to improper processing of crafted IEEE 802.3x flow control pause frames. An attacker could exploit this vulnerability by sending a number of crafted IEEE 802.3x flow control pause frames to an affected device. An exploit could allow the attacker to cause an NPU chip reset and potentially a reload of the affected line card.

Cisco has confirmed the vulnerability and released software updates.

To exploit this vulnerability an attacker must have access to 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.