The Thumbnail Slider With Lightbox plugin for WordPress is vulnerable to Cross-Site Request Forgery in version 1.0. This is due to missing or incorrect nonce validation on the addedit functionality. This makes it possible for unauthenticated attackers to upload arbitrary files via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.