File Browser: Symlink following lets scoped users read, overwrite, and share files outside their filebrowser scope

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.14, it does not stop the HTTP file handlers from following symbolic links before they open, serve, write, share, or list a file. As a result, a scoped user — and in some cases an unauthenticated public-share recipient — can cross the intended scope boundary by following a symlink whose path is lexically inside their scope but whose target is outside it. This vulnerability is fixed in 2.63.14.