chain_sip in Asterisk Open Source 11.x before 11.23.1 and 13.x 13.11.1 and Certified Asterisk 11.6 before 11.6-cert15 and 13.8 before 13.8-cert3 allows remote attackers to cause a denial of service (port exhaustion).
https://issues.asterisk.org/jira/browse/ASTERISK-26272
https://bugzilla.redhat.com/show_bug.cgi?id=1374733
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=838832
http://www.debian.org/security/2016/dsa-3700
http://downloads.asterisk.org/pub/security/AST-2016-007.html