CVE 2015-6831
Multiple use-after-free vulnerabilities in SPL in PHP before 5.4.44, 5.5.x before 5.5.28, and 5.6.x before 5.6.12 allow remote attackers to execute arbitrary code via vectors involving (1) ArrayObject, (2) SplObjectStorage, and (3) SplDoublyLinked
See the 
CVE page on Mitre.org
for more details.
