Asterisk PBX NULL Pointer Dereference Overflow

The host contains an service that is prone to a remote buffer overflow. Description : The remote host appears to be runnning Asterisk PBX, an open-source telephone system. The application suffers from a null pointer dereference overflow in the SIP service. When sending an mailformed SIP packet with no URI and version in the request an attacker can trigger a Denial of Service and shutdown the application resulting in a loss of availability.
Upgrade to Asterisk PBX release 1.4.1 or 1.2.16.