The SIP channel driver (channels/chan_sip.c) in Asterisk Open Source 1.8.17.x through 1.8.22.x, 1.8.23.x before 1.8.23.1, and 11.x before 11.5.1 and Certified Asterisk 1.8.15 before 1.8.15-cert3 and 11.2 before 11.2-cert2 allows remote attackers to cause a denial of service (NULL pointer dereference, segmentation fault, and daemon crash) via an ACK with SDP to a previously terminated channel. NOTE: some of these details are obtained from third party information.
archives.neohapsis.com/archives/bugtraq/2013-08/0175.html
downloads.asterisk.org/pub/security/AST-2013-004.html
osvdb.org/96691
seclists.org/bugtraq/2013/Aug/185
secunia.com/advisories/54534
secunia.com/advisories/54617
www.debian.org/security/2013/dsa-2749
www.mandriva.com/security/advisories?name=MDVSA-2013:223
www.securityfocus.com/bid/62021
www.securitytracker.com/id/1028956
issues.asterisk.org/jira/browse/ASTERISK-21064