In Apache Allura before 1.8.0, unauthenticated attackers may retrieve arbitrary files through the Allura web application. Some webservers used with Allura, such as Nginx, Apache/mod_wsgi or paster may prevent the attack from succeeding. Others, such as gunicorn do not prevent it and leave Allura vulnerable.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.