The ECS WordPress plugin before 4.3.8 does not perform capability or object-ownership checks on its Dynamic Repeater AJAX handlers (gated only by a capability-agnostic nonce that any edit_posts user obtains from the Elementor editor), so a Contributor can write a data-source binding into any post — including admin-authored pages — whose attacker-controlled values are rendered into a widget's repeater output without sanitization, executing JavaScript in the session of any visitor or administrator who views the page.