Cross-site scripting vulnerability (XSS) in (1) admin_index.php, (2) admin_pass.php, (3) admin_modif.php, and (4) admin_suppr.php in MyGuestbook 3.0 allows remote attackers to execute arbitrary PHP code by modifying the location parameter to reference a URL on a remote web server that contains file.php via script injected into the pseudo, email, and message parameters.