CVE-2021-20185: Moodle Client side denial of service via personal message
5.3
CVSS Score
3.1
Basic Information
CVE ID
GHSA ID
EPSS Score
0.66194%
CWE
Published
5/24/2022
Updated
4/23/2024
KEV Status
No
Technology
PHP
PHPTechnical Details
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| moodle/moodle | composer | >= 3.5, < 3.5.16 | 3.5.16 |
| moodle/moodle | composer | >= 3.8, < 3.8.7 | 3.8.7 |
| moodle/moodle | composer | >= 3.9, < 3.9.4 | 3.9.4 |
| moodle/moodle | composer | >= 3.10, < 3.10.1 | 3.10.1 |
Vulnerability Intelligence
Miggo AI
Miggo AIRoot Cause Analysis
The vulnerability stems from missing message size validation in the messaging subsystem. The core messaging function message_send() in message/lib.php is directly responsible for processing and delivering messages. In vulnerable versions, this function lacked input size checks, enabling transmission of unbounded message payloads. The CWE-400/770 mapping confirms this is a resource consumption issue, and the Moodle security advisory (MDL-67782) specifically references messaging component changes. While exact commit details are unavailable, message_send() is the logical entry point where size validation would be implemented, making it the most likely vulnerable function.