source: http://www.securityfocus.com/bid/7151/info

It has been reported that osCommerce does not sufficiently filter URI parameters supplied to multiple osCommerce scripts. 

As a result of this deficiency, it is possible for a remote attacker to create a malicious link containing script code that will be executed in the browser of a legitimate user. All code will be executed within the context of the website running osCommerce. 

This may allow for theft of cookie-based authentication credentials and other attacks.

This vulnerability was reported to affect osCommerce version 2.2ms1, prior versions are reportedly affected.

http://www.example.com/default.php?error_message=%3Cscript%20language=javascript%3Ewindow.alert%28document.cookie%29;%3C/script%3E