W3 Total Cache < 2.10.6 - Author+ Path Traversal via CDN Media Library Import

The W3 Total Cache WordPress plugin before 2.10.6 does not confine a media-import file copy to the document root, nor enforce an effective file-type restriction on it, allowing users with the Author role or higher to plant content that, once an administrator runs the import, copies an arbitrary server-readable file into a publicly served directory, exposing it to unauthenticated retrieval.