Cisco Security Advisory – A vulnerability exists in the Cisco IOS software implementation of Layer 2 Tunneling Protocol (L2TP), which affects limited Cisco IOS software releases. Several features enable the L2TP mgmt daemon process within Cisco IOS software, including but not limited to Layer 2 virtual private networks (L2VPN), Layer 2 Tunnel Protocol Version 3 (L2TPv3), Stack Group Bidding Protocol (SGBP) and Cisco Virtual Private Dial-Up Networks (VPDN). Once this process is enabled the device is vulnerable. This vulnerability will result in a reload of the device when processing a specially crafted L2TP packet. Cisco has released free software updates that address this vulnerability.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/70291/cisco-sa-20080924-l2tp.txt
Source: https://packetstormsecurity.com/files/70291/Cisco-Security-Advisory-20080924-l2tp.html