My Sticky Bar <= 2.8.6 - Unauthenticated SQL Injection via 'stickymenu_contact_lead_form' Action

The My Sticky Bar plugin for WordPress is vulnerable to SQL injection via the `stickymenu_contact_lead_form` AJAX action in all versions up to, and including, 2.8.6. This is due to the handler using attacker-controlled POST parameter names directly as SQL column identifiers in `$wpdb->insert()`. While parameter values are sanitized with `esc_sql()` and `sanitize_text_field()`, the parameter keys are used as-is to build the column list in the INSERT statement. This makes it possible for unauthenticated attackers to inject SQL via crafted parameter names, enabling blind time-based data extraction from the database.