Unauthenticated Cross Site Scripting (XSS) in FV Player 8 <= 8.1.8 versions.

The FV Player 8 plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 8.1.7 via the checkmimetype function. This is due to insufficient file type validation in checkmimetype(), which writes attacker-supplied remote file content to the public uploads directory before any MIME or extension check, combined with a missing capability check on new player creation. This makes it possible for authenticated attackers, with subscriber-level access and above, to upload files that may be executable, which makes remote code execution possible. This requires successfully exploiting a race condition, and is only exploitable if the '[fvplayereditor]' shortcode is present, or the "Enable profile videos" setting is enabled.