Multiple PHP remote file inclusion vulnerabilities in mcGuestbook 1.3 allow remote attackers to execute arbitrary PHP code via a URL in the lang parameter to (1) admin.php, (2) ecrire.php, and (3) lire.php. NOTE: it was later reported that the ecrire.php vector also affects 1.2.  NOTE: this issue might be limited to a race condition during installation or an improper installation, since a completed installation creates an include file that prevents external control of the $lang variable.