The IOHIDFamily kernel extension in Apple iOS before 8 and Apple TV before 7 lacks proper bounds checking on write operations, which allows attackers to execute arbitrary code in the kernel's context via a crafted application.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.