The Madynes research team at INRIA has discovered that Asterisk contains a
null pointer dereferencing error in the SIP channel when handling INVITE
messages. Furthermore qwerty1979 discovered that Asterisk 1.2.x fails to
properly handle SIP responses with return code 0. A remote attacker could
cause an Asterisk server listening for SIP messages to crash by sending a
specially crafted SIP message or answering with a 0 return code.
