Cisco Aggregation Services Router ASR 5000 and ASR 5500 OSPF Denial of Service Vulnerability

A vulnerability in the Open Shortest Path First (OSPF) protocol implementation of the Cisco Aggregation Services Router (ASR) 5000 and ASR 5500 System Software could allow an unauthenticated, remote attacker to cause a partial denial of service (DoS) condition because the OSPF process restarts.

The vulnerability is due to improper input validation of the length fields in the OSPF packet header. An attacker could exploit this vulnerability by sending crafted OSPF packets to the device. An exploit could allow the attacker to cause a partial DoS condition because the OSPF process could restart when parsing the crafted OSPF packet.

Cisco has confirmed the vulnerability and released software updates.

To exploit this vulnerability, the attacker would need to send crafted OSPF packets to the targeted device, making exploitation more difficult in environments that restrict network access from untrusted sources.

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