The kernel in Apple iOS before 9.3 and OS X before 10.11.4 allows attackers to obtain sensitive memory-layout information or cause a denial of service (out-of-bounds read) via a crafted app.
https://support.apple.com/HT206167
https://support.apple.com/HT206166
http://www.securitytracker.com/id/1035353
http://lists.apple.com/archives/security-announce/2016/Mar/msg00004.html
http://lists.apple.com/archives/security-announce/2016/Mar/msg00000.html