channels/chan_iax2.c in Asterisk Open Source 1.8.x before 1.8.15.1 and 10.x before 10.7.1, Certified Asterisk 1.8.11 before 1.8.11-cert7, Asterisk Digiumphones 10.x.x-digiumphones before 10.7.1-digiumphones, and Asterisk Business Edition C.3.x before C.3.7.6 does not enforce ACL rules during certain uses of peer credentials, which allows remote authenticated users to bypass intended outbound-call restrictions by leveraging the availability of these credentials.
http://www.securitytracker.com/id?1027461
http://www.securityfocus.com/bid/55335
http://www.debian.org/security/2012/dsa-2550
http://secunia.com/advisories/50756
http://secunia.com/advisories/50687
http://downloads.asterisk.org/pub/security/AST-2012-013.html