Cross-site scripting (
XSS) occurs where the "step_id" and "CHECKOUT_CZ_BLOWFISH_KEY" variables don't properly sanitize input submitted to the checkout.php script.
This could allow a user to create a specially crafted URL that would execute arbitrary code in a user's browser within the trust relationship between the browser and the server, leading to a loss of integrity.
http://holisticinfosec.org/content/view/81/45/Current fix is to replace the file avactis-system/core/request.php with the attached one.
After a new version is released this bug fix will be available with the update script.