The Meow Lightbox plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'display_name + comment' parameter in all versions up to, and including, 5.6.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This vulnerability is only exploitable when the plugin's Output Buffering option is enabled (disabled by default), and requires the attacker to have at least one previously approved comment on the site so that subsequent comments are auto-approved by WordPress core.