CVE-2021-20281

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-15 · updated 2026-06-17
Weakness: CWE-200

Description

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.

Affected products

Fedoraproject Fedora: 32, 34
Moodle: from 3.5.0 before 3.5.17; from 3.8.0 before 3.8.8; from 3.9.0 before 3.9.5; from 3.10.0 before 3.10.2 — fixed in 3.10.2, 3.5.17, 3.8.8, 3.9.5

How to fix

Upgrade to a fixed version: Moodle 3.10.2, 3.5.17, 3.8.8, 3.9.5. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1939041
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AFSNJ7XHVTC52RSRX2GBQFF3VEEAY2MS/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UFH5DDMU5TZ3JT4Q52WMRAHACA5MHIMT/
https://moodle.org/mod/forum/discuss.php?d=419652
https://bugzilla.redhat.com/show_bug.cgi?id=1939041
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AFSNJ7XHVTC52RSRX2GBQFF3VEEAY2MS/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UFH5DDMU5TZ3JT4Q52WMRAHACA5MHIMT/
https://moodle.org/mod/forum/discuss.php?d=419652

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