Variable overwrite vulnerability in groupit/base/groupit.start.inc in Groupit 2.00b5 allows remote attackers to conduct remote file inclusion attacks and execute arbitrary PHP code via arguments that are written to $_GLOBALS, as demonstrated using a URL in the c_basepath parameter to (1) content.php, (2) userprofile.php, (3) password.php, (4) dispatch.php, and (5) deliver.php in html/, and possibly (6) load.inc.php and related files.