The kernel in Apple iOS before 8 and Apple TV before 7 uses a predictable random number generator during the early portion of the boot process, which allows attackers to bypass certain kernel-hardening protection mechanisms by using a user-space process to observe data related to the random numbers.
http://archives.neohapsis.com/archives/bugtraq/2014-09/0106.html
http://archives.neohapsis.com/archives/bugtraq/2014-09/0107.html
http://archives.neohapsis.com/archives/bugtraq/2014-10/0101.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/96096
https://support.apple.com/kb/HT6535
http://support.apple.com/kb/HT6441