Integer overflow in the simulator in Swift in Apple Xcode before 6.3 allows context-dependent attackers to cause a denial of service or possibly have unspecified other impact by triggering an incorrect result of a type conversion.
https://support.apple.com/HT204663
http://www.securitytracker.com/id/1032049
http://lists.apple.com/archives/security-announce/2015/Apr/msg00004.html