Not really, just an unintuitive security feature. You still need the user's permission to access that folder, but that permission is then persistent. I consider it a UX bug for sure but not an exploit.

I agree, it's a ui/ux problem. It would seem that using the open file dialog should also request access but I'm guessing that was too intrusive and the user action is seen as implicit authorization. Security is one of those things that should aways be explicit though.