Buffer underflow in the PHP_FILTER_TRIM_DEFAULT macro in the filtering extension (ext/filter) in PHP 5.2.0 allows context-dependent attackers to execute…

Buffer underflow in the PHP_FILTER_TRIM_DEFAULT macro in the filtering extension (ext/filter) in PHP 5.2.0 allows context-dependent attackers to execute arbitrary code by calling filter_var with certain modes such as FILTER_VALIDATE_INT, which causes filter to write a null byte in whitespace that precedes the buffer.