CVE-2021-3943 Moodle vulnerable to RCE via unsafe deserialization

What is CVE-2021-3943?

CVE-2021-3943 is a critical code injection vulnerability in Moodle Moodle, published on 22 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw was found in Moodle in versions 3.11 to 3.11.3, 3.10 to 3.10.7, 3.9 to 3.9.10 and earlier unsupported versions. A remote code execution risk when restoring backup files was identified.

Weakness: CWE-20

Which versions are affected by CVE-2021-3943?

7 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-2021-3943?

Upgrade moodle/moodle to a fixed version for your release line: 3.10.8, 3.11.4 or 3.9.11.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2021-3943 being exploited?

There is no known exploitation of CVE-2021-3943 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-2021-3943, GHSA-8jhp-2gcr-qw96, UBUNTU-CVE-2021-3943.