Use-after-free vulnerability in the SPL unserialize implementation in ext/spl/spl_array.c in PHP before 5.4.44, 5.5.x before 5.5.28, and 5.6.x before 5.6.12 allows remote attackers to execute arbitrary code via crafted serialized data that triggers misuse of an array field.
https://security.gentoo.org/glsa/201606-10
https://bugs.php.net/bug.php?id=70068