Smart Popup by Supsystic < 2.0.2 - Admin+ SSTI via Popup Text Block

The Smart Popup by Supsystic WordPress plugin before 2.0.2 does not prevent template-injection payloads from being stored in a popup text block and later evaluated by its template engine, because the filter meant to strip template delimiters runs before a decoding step that reconstructs them, allowing an authenticated administrator to execute arbitrary template expressions server-side and read PHP constants such as the site's database credentials and authentication keys.