The IAX2 channel driver (chan_iax2) for Asterisk 1.2.x before 1.2.9 and 1.0.x before 1.0.11 allows remote attackers to cause a denial of service (crash) and execute arbitrary code via truncated IAX 2 (IAX2) video frames, which bypasses a length check and leads to a buffer overflow involving negative length check. NOTE: the vendor advisory claims that only a DoS is possible, but the original researcher is reliable.
https://exchange.xforce.ibmcloud.com/vulnerabilities/27045
http://www.vupen.com/english/advisories/2006/2181
http://www.securityfocus.com/bid/18295
http://www.securityfocus.com/archive/1/436671/100/0/threaded
http://www.securityfocus.com/archive/1/436127/100/0/threaded
http://www.novell.com/linux/security/advisories/2006_38_security.html
http://www.gentoo.org/security/en/glsa/glsa-200606-15.xml
http://www.debian.org/security/2006/dsa-1126
http://www.asterisk.org/node/95
http://securitytracker.com/id?1016236
http://secunia.com/advisories/21222
http://secunia.com/advisories/20899