source: http://www.securityfocus.com/bid/9238/info

It has been reported that osCommerce may be prone to a cross-site scripting vulnerability that may allow an attacker to construct a malicious link containing HTML or script code that may be rendered in a user's browser.

Successful exploitation of this attack may allow an attacker to steal cookie-based authentication credentials. Other attacks are also possible.

Although unconfirmed, osCommerce versions 2.2 Milestone 1 and 2.2 Milestone 2 may be vulnerable to this issue. 

https://www.example.com/?osCsid="><iframe src=http://www.example.com></iframe>