The PJSIP channel driver in Asterisk Open Source 12.x before 12.1.1, when qualify_frequency "is enabled on an AOR and the remote SIP server challenges for authentication of the resulting OPTIONS request," allows remote attackers to cause a denial of service (crash) via a PJSIP endpoint that does not have an associated outgoing request.
https://issues.asterisk.org/jira/browse/ASTERISK-23210
http://lists.fedoraproject.org/pipermail/package-announce/2014-March/130426.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-March/130400.html
http://downloads.asterisk.org/pub/security/AST-2014-003.html
http://downloads.asterisk.org/pub/security/AST-2014-003-12.diff