Elementor Website Builder <= 4.0.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via REST API

The Elementor Website Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the _elementor_data meta field in versions up to, and including, 4.0.4. This is due to insufficient input sanitization when processing form-encoded REST API requests. The plugin registers the _elementor_data meta field with show_in_rest but omits a sanitize_callback, relying instead on a rest_pre_insert_post filter (sanitize_post_data function) that only sanitizes JSON-encoded request bodies. When a contributor sends a form-encoded PATCH request to the WordPress REST API, the json_decode() call on the raw body returns null, causing all sanitization to be skipped. The unsanitized data is then stored via update_post_meta() and later output without escaping through multiple widget sinks including the HTML widget's print_unescaped_setting() function. 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.

An attacker needs Contributor access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Elementor Website Builder 4.0.5 closes this, and updating the plugin is the step that ends it.

• Firewall
• Alerts