The JetEngine plugin for WordPress is vulnerable to SQL Injection via the Custom Content Type (CCT) REST API search endpoint in all versions up to, and including, 3.8.6.1. This is due to the `_cct_search` parameter being interpolated directly into a SQL query string via `sprintf()` without sanitization or use of `$wpdb->prepare()`. WordPress REST API's `wp_unslash()` call on `$_GET` strips the `wp_magic_quotes()` protection, allowing single-quote-based injection. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. The Custom Content Types module must be enabled with at least one CCT configured with a public REST GET endpoint for exploitation.