Demi <= 0.0.6 - Unauthenticated Arbitrary Directory Deletion via demi_restore_step AJAX action

Summary

The Demi – One Click Demo Import, WP Backup & Site Migration plugin for WordPress is vulnerable to Arbitrary Directory Deletion in all versions up to, and including, 0.0.7. The vulnerability exists because the plugin stores its HMAC signing key and per-step restore token as dotfiles inside a publicly accessible subdirectory of the WordPress uploads folder — without any `.htaccess` or index file protection — and the `demi_restore_step` AJAX handler, registered for unauthenticated callers, explicitly accepts possession of the on-disk signing key as a standalone alternative to WordPress capability and nonce checks; an unauthenticated attacker who retrieves the exposed key can forge a valid signed state envelope to invoke `CleanDir::execute()` with a caller-supplied absolute path that is subject to no allow-list or path-canonicalization check. This makes it possible for unauthenticated attackers to recursively delete arbitrary directories on the server.