Quiz and Survey Master (QSM) < 11.1.1 - Unauthenticated Shortcode Injection

Description

The plugin is vulnerable to Arbitrary Shortcode Executiondue to insufficient input sanitization and the execution of do_shortcode() on user-submitted quiz answer text. User-submitted answers pass through sanitize_text_field() and htmlspecialchars(), which only strip HTML tags but do not encode or remove shortcode brackets [ and ]. When quiz results are displayed, the plugin calls do_shortcode() on the entire results page output (including user answers), causing any injected shortcodes to be executed. This makes it possible for unauthenticated attackers to inject arbitrary WordPress shortcodes such as [qsm_result id=X] to access other users' quiz submissions without authorization, as the qsm_result shortcode lacks any authorization checks.