Asterisk Project Security Advisory – An attacker can cause Asterisk to crash remotely by sending malformed RTP text frames. While the attacker can cause Asterisk to crash, he cannot execute arbitrary remote code with this exploit.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/80029/AST-2009-004.txt
Source: https://packetstormsecurity.com/files/80029/Asterisk-Project-Security-Advisory-2009-004.html