The plugin called Responsive Lightbox & Gallery for WordPress has a security issue where harmful code can be added to a website through the SwipeBox feature. This can happen in any version of the plugin, including the latest one (2.5.1), because it does not properly clean up the input and output. This means that someone who has permission to contribute to the website (such as a logged-in user) could add dangerous code to a page, which will run whenever someone visits that page.