Vulnerability DatabaseCVE-2021-20185
Mend.io Vulnerability Database
The largest open source vulnerability database
What is a Vulnerability ID?
New vulnerability? Tell us about it!
CVE-2021-20185
Published:January 28, 2021
Updated:May 17, 2026
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 Packages
moodle/moodle (PHP):
Affected version(s) >=v3.9.0 <v3.9.4
Fix Suggestion:
Update to version v3.9.4
moodle/moodle (PHP):
Affected version(s) =v3.10.0 <v3.10.1
Fix Suggestion:
Update to version v3.10.1
moodle/moodle (PHP):
Affected version(s) >=v3.5.0 <v3.5.16
Fix Suggestion:
Update to version v3.5.16
moodle/moodle (PHP):
Affected version(s) >=v3.8.0 <v3.8.7
Fix Suggestion:
Update to version v3.8.7
Related Resources (3)
https://moodle.org/mod/forum/discuss.php?d=417168
https://github.com/moodle/moodle
https://nvd.nist.gov/vuln/detail/CVE-2021-20185
Do you need more information?
Contact Us
CVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Uncontrolled Resource Consumption
CWE-400
Allocation of Resources Without Limits or Throttling
CWE-770
EPSS
Base Score:
0.38