The IAX2 channel driver (chan_iax2) in Asterisk before 20070504 does not properly null terminate data, which allows remote attackers to trigger loss of transmitted data, and possibly obtain sensitive information (memory contents) or cause a denial of service (application crash), by sending a frame that lacks a 0 byte.
https://exchange.xforce.ibmcloud.com/vulnerabilities/34085
http://www.vupen.com/english/advisories/2007/1661
http://www.securityfocus.com/bid/23824
http://www.novell.com/linux/security/advisories/2007_34_asterisk.html
http://www.debian.org/security/2007/dsa-1358
http://secunia.com/advisories/25582