The remote web server uses a version of PHP that is affected by a remote code execution vulnerability.
PHP versions prior to 5.3.10 are reportedly affected by a code execution vulnerability. Specifically, the fix for the hash collision denial of service vulnerability (CVE-2011-4885) itself has introduced a remote code execution vulnerability in the php_register_variable_ex() in the file 'php_variables.c'. A new configuration variable, 'max_input_vars', was added as part of the fix. If the number of input variables exceeds this value and the variable being processed is an array, code execution can occur.
Upgrade to PHP version 5.3.10 or later.