source: https://www.securityfocus.com/bid/9563/info

X-Cart has been reported to be prone to an issue that may allow remote attackers to view any web server readable files on the affected system. The issue is caused by a failure of the application to sanitize values specified by parameters in the URI. This issue has been reported to affect the 'auth.php' script.

It has been reported that there is also an information disclosure issue with the 'general.php' script that resides in the 'admin' directory of the application. The 'mode' URI parameter can be set to request information on the current PHP and Perl software versions, allowing potential attackers the gain access to sensitive system details. 

http://servername/customer/auth.php?config[General][shop_closed]=Y&shop_closed_file=../../../../../../../etc/passwd