source: https://www.securityfocus.com/bid/5249/info

Macromedia Sitespring is a J2EE-compliant product for managing website production. The Macromedia Sitespring server runs on Microsoft Windows operating systems.

A cross-site scripting issue has been reported in the default error page used by Sitespring. When an HTTP 500 error is returned, some user-supplied data is included in the generated HTML. Since this data isn't properly sanitized, an attacker may be able to include arbitrary HTML, including JavaScript. 

http://server/error/500error.jsp?et=1<script>alert('KPMG')</script>