Asterisk Project Security Advisory – Javantea found multiple security issues in IAX2 including an incomplete 3-way handshake.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/65714/AST-2008-006.txt
Source: https://packetstormsecurity.com/files/65714/AST-2008-006.txt.html