register.php in S8Forum 3.0 allows remote attackers to execute arbitrary PHP commands by creating a user whose name ends in a .php extension and entering the…

register.php in S8Forum 3.0 allows remote attackers to execute arbitrary PHP commands by creating a user whose name ends in a .php extension and entering the desired commands into the E-mail field, which creates a web-accessible .php file that can be called by the attacker, as demonstrated using a "system($cmd)" E-mail address with a "any_name.php" username.