The TRE library in Libc in Apple iOS before 8.4.1 and OS X before 10.10.5 allows context-dependent attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted regular expression, a different vulnerability than CVE-2015-3796 and CVE-2015-3797.
Improper Restriction of Operations within the Bounds of a Memory Buffer The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.