Icegram Engage <= 3.1.42 - Authenticated (Contributor+) Second-Order SQL Injection via 'messages[][id]' Parameter

The Icegram Engage – Popups, Optins, CTAs & Lead Generation plugin for WordPress is vulnerable to second-order SQL Injection via 'messages[][id]' Parameter in all versions up to, and including, 3.1.42 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for authenticated attackers, with contributor-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. The injection is second-order: the malicious id value is first persisted to post meta via the save_campaign_preview() AJAX action (gated by a nonce check and edit_post capability, requiring Editor-level access or above), and only executed as SQL when a subsequent preview request triggers get_message_data() to interpolate the stored value directly into a SQL IN() clause without $wpdb->prepare() or integer casting.