Zend/zend_exceptions.c in PHP before 5.4.44, 5.5.x before 5.5.28, and 5.6.x before 5.6.12 does not validate certain Exception objects, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) or trigger unintended method execution via crafted serialized data.<a href=http://cwe.mitre.org/data/definitions/476.html>CWE-476: NULL Pointer Dereference</a> http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-8876