Calendar in Apple iOS before 9.3.3 allows remote attackers to cause a denial of service (NULL pointer dereference and device restart) via a crafted invitation.
https://support.apple.com/HT206902
http://www.securitytracker.com/id/1036344
http://www.securityfocus.com/bid/91825
http://lists.apple.com/archives/security-announce/2016/Jul/msg00001.html