I have some major issues trying to complete this document: http://waltercedric.com/Mambo/Java/Security/Typical-issues-with-webapplications-v1.5-4.html
Mambo do not let me add new text in the content of this article.  that is why I now propose it as a PDF download (this PDF contains much more example of we applications security issues than the html version). Enjoy.

Download Typical issues with webapplications v1.5 .pdf