AppleUSBNetworking in Apple iOS before 9.3 and OS X before 10.11.4 allows physically proximate attackers to execute arbitrary code in a privileged context or cause a denial of service (memory corruption) via a crafted USB device.
http://lists.apple.com/archives/security-announce/2016/Mar/msg00000.html
http://lists.apple.com/archives/security-announce/2016/Mar/msg00004.html
https://support.apple.com/HT206166