The Qwizcards | online quizzes and flashcards WordPress plugin through 3.9.4 does not sanitise and escape the "_stylesheet" parameter before outputting it back in the page, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin or any other user.
https://wpscan.com/vulnerability/ff827f67-712e-4ab6-b6aa-7f5e6ff1283a/