It was possible for some users without permission to view other users’ full names to do so via the online users block in moodle before 3.10.2, 3.9.5, 3.8.8, 3.5.17.
bugzilla.redhat.com/show_bug.cgi?id=1939041
github.com/moodle/moodle
github.com/moodle/moodle/commit/33d6017287e1835513a3de8edd3fbf7a6a90af9c
lists.fedoraproject.org/archives/list/[email protected]/message/AFSNJ7XHVTC52RSRX2GBQFF3VEEAY2MS
lists.fedoraproject.org/archives/list/[email protected]/message/UFH5DDMU5TZ3JT4Q52WMRAHACA5MHIMT
moodle.org/mod/forum/discuss.php?d=419652
nvd.nist.gov/vuln/detail/CVE-2021-20281