Cisco ASR 5500 Series with DPC2 Cards SESSMGR Denial of Service Vulnerability

A vulnerability in the Slowpath of StarOS for Cisco ASR 5500 Series routers with Data Processing Card 2 (DPC2) could allow an unauthenticated, remote attacker to cause a subset of the subscriber sessions to be disconnected, resulting in a partial denial of service (DoS) condition.

The vulnerability is due to improper processing during the handoff of reassembled IPv4 or IPv6 packets. An attacker could exploit this vulnerability by sending crafted IPv4 or IPv6 fragments across the ASR 5500 Series router. An exploit could allow the attacker to cause an instance of the sessmgr service on the affected device to reload. A reload of the sessmgr service will cause all subscriber sessions serviced by that task to be disconnected, resulting in a denial of service (DoS) condition.

Cisco has released software updates that address this vulnerability. There is a workaround that addresses this vulnerability.

This advisory is available at the following link:

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161102-asr[“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161102-asr”]