WordPress WP e-Commerce Plugin 'cart_messages' Parameter Cross-site Scripting Vulnerability

Summary
This host is installed with WordPress WP e-Commerce plugin and is prone to cross-site scripting vulnerability.
Impact
Successful exploitation will allow attacker to insert arbitrary HTML and script code, which will be executed in a user's browser session in the context of an affected site when the malicious data is being viewed. Impact Level: Application
Solution
No solution or patch was made available for at least one year since disclosure of this vulnerability. Likely none will be provided anymore. General solution options are to upgrade to a newer release, disable respective features, remove the product or replace the product by another one.
Insight
The flaw is due to improper validation of user-supplied input passed via the 'cart_messages[]' parameter to '/wp-content/plugins/wp-e-commerce /wpsc-theme/wpsc-cart_widget.php', which allows attacker to execute arbitrary HTML and script code on the user's browser session in the security context of an affected site.
Affected
WordPress WP e-Commerce Plugin version 3.8.6 and prior.
References