CVE-2023-23921: Moodle

Medium severity, CVSS 6.1. EPSS: 0.8% chance of exploitation in the next 30 days.

The vulnerability was found Moodle which exists due to insufficient sanitization of user-supplied data in some returnurl parameters. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website. This flaw allows a remote attacker to perform cross-site scripting (XSS) attacks.

Affected products

• Moodle Moodle: from 3.9.0, before 3.9.19 (fixed in 3.9.19); from 3.11.0, before 3.11.12 (fixed in 3.11.12); from 4.0.0, before 4.0.6 (fixed in 4.0.6); version 4.1.0 only

Published 2023-02-17. Last modified 2026-06-17.