Butor Portal before 1.0.27 is affected by a Path Traversal vulnerability leading to a pre-authentication arbitrary file download

Butor Portal before 1.0.27 is affected by a Path Traversal vulnerability leading to a pre-authentication arbitrary file download. Effectively, a remote anonymous user can download any file on servers running Butor Portal. WhiteLabelingServlet is responsible for this vulnerability. It does not properly sanitize user input on the theme t parameter before reusing it in a path. This path is then used without validation to fetch a file and return its raw content to the user via the /wl?t=../../...&h= substring followed by a filename.