source: http://www.securityfocus.com/bid/4125/info

GNUJSP is a freely available, open-source implementation of Sun's Java Server Pages. It will run on most Unix and Linux variants, as well as Microsoft Windows NT/2000 operating systems.

It has been reported that a remote attacker may disclose the contents of directories via a specially crafted web request. This may be exploited to list directories, read the contents of arbitrary web-readable files, and disclose script source code. The attacker simply appends the name of the directory and/or file to be disclosed to a web request for /servlets/gnujsp/.

It should be noted that this may allow an attacker to circumvent .htaccess files.

This issue may be the result of a configuration error. 

http://site/servlets/gnujsp/[dirname]/[file]