The MaxiBlocks Builder plugin for WordPress is vulnerable to arbitrary media file deletion due to insufficient file ownership validation on the 'maxi_remove_custom_image_size' AJAX action in all versions up to, and including, 2.1.8. This makes it possible for authenticated attackers, with Author-level access and above, to delete arbitrary files in the wp-content/uploads directory, including files uploaded by other users and administrators.
https://plugins.trac.wordpress.org/browser/maxi-blocks/trunk/core/class-maxi-image-crop.php#L44
https://plugins.trac.wordpress.org/browser/maxi-blocks/tags/2.1.7/core/class-maxi-image-crop.php#L44
https://github.com/maxi-blocks/maxi-blocks/commit/3dff1db57bfb4e6c14fa7fd42037178d1d0ce199