CVE-2021-20185: Moodle

Medium severity, CVSS 5.3. EPSS: 1.4% chance of exploitation in the next 30 days.

It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that messaging did not impose a character limit when sending messages, which could result in client-side (browser) denial of service for users receiving very large messages.

Affected products

• Moodle Moodle: from 3.5.0, before 3.5.16 (fixed in 3.5.16); from 3.8.0, before 3.8.7 (fixed in 3.8.7); from 3.9.0, before 3.9.4 (fixed in 3.9.4); version 3.10.0 only

Published 2021-01-28. Last modified 2026-06-17.