The WebKit Canvas implementation in Apple iOS before 9.3.2, Safari before 9.1.1, and tvOS before 9.2.1 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site.
http://lists.apple.com/archives/security-announce/2016/May/msg00001.html
http://lists.apple.com/archives/security-announce/2016/May/msg00002.html
http://lists.apple.com/archives/security-announce/2016/May/msg00005.html
https://support.apple.com/HT206564
https://support.apple.com/HT206565
https://support.apple.com/HT206568