PHP remote file inclusion vulnerability in visitor.php in Butterfly online visitors counter 1.08, when used with certain older versions of PHP with improper SERVER superglobal handling, allows remote attackers to execute arbitrary PHP code via a URL in the _SERVER[DOCUMENT_ROOT] parameter.  NOTE: it could be argued that this vulnerability is caused by a problem in PHP and the proper fix should be in PHP; if so, then this should not be treated as a vulnerability in Butterfly online visitors counter.