CVE-2026-3339: fallo de gravedad baja en fahadmahmood Keep Backup Daily

The Keep Backup Daily plugin for WordPress is vulnerable to Limited Path Traversal in all versions up to, and including, 2.1.1 via the `kbd_open_upload_dir` AJAX action. This is due to insufficient validation of the `kbd_path` parameter, which is only sanitized with `sanitize_text_field()` - a function that does not strip path traversal sequences. This makes it possible for authenticated attackers, with Administrator-level access and above, to list the contents of arbitrary directories on the server outside of the intended uploads directory.