CVE-2026-2412: Quiz and Survey Master (QSM) <= 10.3.5 - Authenticated (Contributor+) SQL Injection via 'merged_question' Parameter

The Quiz and Survey Master (QSM) plugin for WordPress is vulnerable to SQL Injection via the 'mergedquestion' parameter in all versions up to, and including, 10.3.5. This is due to insufficient sanitization of user-supplied input before being used in a SQL query. The sanitizetextfield() function applied to the mergedquestion parameter does not prevent SQL metacharacters like ), OR, AND, and # from being included in the value, which is then directly concatenated into a SQL IN() clause without using $wpdb->prepare() or casting values to integers. 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.