wpDiscuz before 7.6.47 - Unauthenticated Email Notification Flood via wpdCheckNotificationType

wpDiscuz before 7.6.47 contains an unauthenticated denial of service vulnerability that allows anonymous users to trigger mass notification emails by exploiting the checkNotificationType() function. Attackers can repeatedly call the wpdiscuz-ajax.php endpoint with arbitrary postId and comment_id parameters to flood subscribers with notifications, as the handler lacks nonce verification, authentication checks, and rate limiting.