In Pallets Werkzeug before 0.15.5, SharedDataMiddleware mishandles drive names (such as C:) in Windows pathnames.
https://palletsprojects.com/blog/werkzeug-0-15-5-released/
http://packetstormsecurity.com/files/163398/Pallets-Werkzeug-0.15.4-Path-Traversal.html