Asterisk Project Security Advisory – A remotely exploitable crash vulnerability exists in the SIP channel driver if an ACK with SDP is received after the channel has been terminated. The handling code incorrectly assumes that the channel will always be present…. Asterisk Project Security Advisory – A remotely exploitable crash vulnerability exists in the SIP channel driver if an ACK with SDP is received after the channel has been terminated. The handling code incorrectly assumes that the channel will always be present.

Read more http://packetstormsecurity.com/files/122990/AST-2013-004.txt