The HD Quiz plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions 2.2.0 to 2.2.1. This is due to missing or incorrect nonce validation on the hdq_validate_nonce function. This makes it possible for unauthenticated attackers to delete or modify quizzes and questions, create new quizzes, and change plugin settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.2/includes/functions.php#L40
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/functions.php#L39
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/actions-ajax.php#L87
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/actions-ajax.php#L7
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/actions-ajax.php#L68
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/actions-ajax.php#L53
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/actions-ajax.php#L179
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.1/includes/actions-ajax.php#L155
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/functions.php#L39
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/actions-ajax.php#L87
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/actions-ajax.php#L7
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/actions-ajax.php#L68
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/actions-ajax.php#L53
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/actions-ajax.php#L179
https://plugins.trac.wordpress.org/browser/hd-quiz/tags/2.2.0/includes/actions-ajax.php#L155