Cisco Security Advisory – Cisco IOS XR will reset a Border Gateway Protocol (BGP) peering session when receiving a specific invalid BGP update. The vulnerability manifests when a BGP peer announces a prefix with a specific invalid attribute. On receipt of this prefix, the Cisco IOS XR device will restart the peering session by sending a notification. The peering session will flap until the sender stops sending the invalid/corrupt update.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/80428/cisco-sa-20090818-bgp.txt
Source: https://packetstormsecurity.com/files/80428/Cisco-Security-Advisory-20090818-bgp.html