A vulnerability in the peer-to-peer message processing functionality of Cisco Packet Data Network Gateway could allow an unauthenticated, remote attacker to cause the Session Manager (SESSMGR) process on an affected device to restart, resulting in a denial of service (DoS) condition. The vulnerability is due to incorrect validation of peer-to-peer packet headers. An attacker could exploit this vulnerability by sending a crafted peer-to-peer packet through an affected device. A successful exploit could allow the attacker to cause the SESSMGR process on the affected device to restart unexpectedly, which could briefly impact traffic while the SESSMGR process restarts and result in a DoS condition. Cisco Bug IDs: CSCvg88786.