The design of the dialplan functionality in Asterisk Open Source 1.2.x, 1.4.x, and 1.6.x; and Asterisk Business Edition B.x.x and C.x.x, when using the ${EXTEN} channel variable and wildcard pattern matches, allows context-dependent attackers to inject strings into the dialplan using metacharacters that are injected when the variable is expanded, as demonstrated using the Dial application to process a crafted SIP INVITE message that adds an unintended outgoing channel leg. NOTE: it could be argued that this is not a vulnerability in Asterisk, but a class of vulnerabilities that can occur in any program that uses this feature without the associated filtering functionality that is already available.
https://exchange.xforce.ibmcloud.com/vulnerabilities/56397
http://www.vupen.com/english/advisories/2010/0439
http://www.securitytracker.com/id?1023637
http://www.securityfocus.com/archive/1/509608/100/0/threaded
http://svn.asterisk.org/svn/asterisk/branches/1.2/README-SERIOUSLY.bestpractices.txt
http://secunia.com/advisories/39096
http://secunia.com/advisories/38641
http://lists.fedoraproject.org/pipermail/package-announce/2010-March/037679.html