chan_skinny.c in the Skinny (aka SCCP) channel driver in Certified Asterisk 1.8.11-cert before 1.8.11-cert2 and Asterisk Open Source 1.8.x before 1.8.12.1 and 10.x before 10.4.1 allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) by closing a connection in off-hook mode.
https://exchange.xforce.ibmcloud.com/vulnerabilities/75937
http://www.securitytracker.com/id?1027103
http://www.securityfocus.com/bid/53723
http://www.debian.org/security/2012/dsa-2493
http://secunia.com/advisories/49303
http://downloads.asterisk.org/pub/security/AST-2012-008.html
http://archives.neohapsis.com/archives/bugtraq/2012-05/0145.html