The tutor_mark_answer_as_correct AJAX action from the Tutor LMS – eLearning and online course solution WordPress plugin before 1.7.7 was vulnerable to blind and time based SQL injections that could be exploited by students.
https://www.wordfence.com/blog/2021/03/several-vulnerabilities-patched-in-tutor-lms-plugin/
https://wpscan.com/vulnerability/d5a00322-7098-4f8d-8e5e-157b63449c17