Asterisk Project Security Advisory – A remote crash vulnerability exists in the SIP channel driver allow for a denial of service condition.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/75616/AST-2009-002.txt
Source: https://packetstormsecurity.com/files/75616/Asterisk-Project-Security-Advisory-AST-2009-002.html