WordPress CVE-2026-4406

The Gravity Forms plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the form_ids parameter in the gform_get_config AJAX action in all versions up to, and including, 2.9.30. This is due to the GFCommon::send_json() method outputting JSON-encoded data wrapped in HTML comment delimiters using echo and wp_die(), which serves the response with a Content-Type: text/html header instead of application/json. The wp_json_encode() function does not HTML-encode angle brackets within JSON string values, allowing injected HTML/script tags in form_ids array values to be parsed and executed by the browser. The required config_nonce is generated with wp_create_nonce('gform_config_ajax') and is publicly embedded on every page that renders a Gravity Forms form, making it identical for all unauthenticated visitors within the same 12-hour nonce tick. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. This vulnerability cannot be exploited against users who are authenticated on the target system, but could be used to alter the target page.