Multi Uploader for Gravity Forms <= 1.1.8 - Missing Authorization to Unauthenticated Arbitrary Media Deletion

The Multi Uploader for Gravity Forms plugin for WordPress is vulnerable to unauthorized arbitrary media deletion in all versions up to, and including, 1.1.8. This is due to missing capability checks in the `plupload_ajax_delete_file()` function, which is registered via `wp_ajax_nopriv_gfmu_delete_file`. The nonce intended for CSRF protection is exposed on any public-facing page containing a multi-uploader form field via the `GFMU_options` JavaScript object. This makes it possible for unauthenticated attackers to permanently delete any WordPress media attachment by supplying its attachment ID, potentially leading to complete media library destruction.