The Sunshine Photo Cart plugin for WordPress is vulnerable to a type of attack known as Cross-Site Request Forgery in versions up to, and including, 2.8.28. This means that malicious actors can potentially manipulate the plugin to save custom post data without authorization if they can convince a site administrator to take an action, such as clicking on a link. This is because the plugin does not properly validate nonce, which is a security measure used to detect and prevent these types of attacks.