The php_register_variable_ex function in php_variables.c in PHP 5.3.9 allows remote attackers to execute arbitrary code via a request containing a large number of variables, related to improper handling of array variables. NOTE: this vulnerability exists because of an incorrect fix for CVE-2011-4885.

PHP before 5.3.9 computes hash values for form parameters without restricting the ability to trigger hash collisions predictably, which allows remote attackers to cause a denial of service (CPU consumption) by sending many crafted parameters.