In Moodle 3.x, course creators are able to change system default settings for courses.
github.com/moodle/moodle
github.com/moodle/moodle/commit/6e861be6b7d49c5ac4583ae46762a28ede5785ad
github.com/moodle/moodle/commit/915f801546a5c3618feab897072c985abfce57df
moodle.org/mod/forum/discuss.php?d=355556
nvd.nist.gov/vuln/detail/CVE-2017-7532
web.archive.org/web/20210614032706/www.securityfocus.com/bid/99617