The LightPress Lightbox plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the group attribute in the [gallery] shortcode in all versions up to, and including, 2.3.4. This is due to the plugin modifying gallery shortcode output to include the group attribute value without proper escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.