Cisco Security Advisory – Cisco IOS devices that are configured with Cisco IOS Zone-Based Policy Firewall Session Initiation Protocol (SIP) inspection are vulnerable to denial of service (DoS) attacks when processing a specific SIP transit packet. Exploitation of the vulnerability could result in a reload of the affected device.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/81596/cisco-sa-20090923-ios-fw.txt
Source: https://packetstormsecurity.com/files/81596/Cisco-Security-Advisory-20090923-ios-fw.html