CVE-2023-23921 Moodle: reflected xss risk in some returnurl parameters

What is CVE-2023-23921?

CVE-2023-23921 is a medium-severity cross-site scripting vulnerability in Moodle Moodle, published on 17 Feb 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-79

Which versions are affected by CVE-2023-23921?

9 open source packages ship an affected version, including moodle/moodle and moodle. It affects 1 product.

Products include Moodle Moodle.

How do I fix CVE-2023-23921?

Upgrade moodle/moodle to a fixed version for your release line: 3.9.19, 3.11.12, 4.0.6 or 4.1.1.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2023-23921 being exploited?

There is no known exploitation of CVE-2023-23921 in the wild and no public exploit code.

Other vulnerabilities in Moodle Moodle

• CVE-2006-4935 File upload in n/a Critical 10.0
• CVE-2006-4936 Moodle does not properly validate module instance id Critical 10.0
• CVE-2004-2233 Unknown "front page vulnerability with Moodle servers" for Moodle before 1.3.2 has unknown impact and attack vectors. Critical 10.0
• CVE-2004-2235 Cross-site scripting in n/a Critical 10.0
• CVE-2004-2236 Other in n/a Critical 10.0

All Moodle Moodle vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-moodle-2023-23921, GHSA-97qf-pq7x-964m, UBUNTU-CVE-2023-23921.