The Document Gallery plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'dgthumberwebhook' Action Request Body in all versions up to, and including, 5.1.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires that logging be enabled in the plugin's Advanced settings, which is only the default state when WPDEBUG is true; otherwise an administrator must manually enable it.