CVE-2021-36395 : What You Need to Know

In Moodle, the file repository's URL parsing required additional recursion handling to mitigate the risk of recursion denial of service.

Understanding CVE-2021-36395

This CVE affects the Moodle learning platform due to a vulnerability related to URL parsing in the file repository.

What is CVE-2021-36395?

The CVE-2021-36395 relates to a denial of service risk caused by a lack of proper recursion handling in the file repository's URL parsing in Moodle.

The Impact of CVE-2021-36395

The impact of this CVE is the potential for denial of service attacks that could disrupt the normal functioning of Moodle instances, leading to service outages.

Technical Details of CVE-2021-36395

This section provides more insights into the technical aspects of the vulnerability in Moodle.

Vulnerability Description

The vulnerability arises from insufficient recursion handling in the URL parsing mechanism of the file repository in Moodle, leading to a denial of service risk.

Affected Systems and Versions

The affected systems include Moodle versions 3.11, 3.10 to 3.10.4, 3.9 to 3.9.7, and any earlier unsupported versions that utilize the file repository feature.

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting malicious requests that trigger the inadequate recursion handling in the URL parsing, causing denial of service.

Mitigation and Prevention

Protecting your Moodle instance involves taking immediate steps and adopting long-term security practices.

Immediate Steps to Take

Apply the latest security patches provided by Moodle to mitigate the CVE-2021-36395 vulnerability.
Monitor and restrict access to the affected file repository to prevent unauthorized exploitation.

Long-Term Security Practices

Regularly update Moodle to the latest stable version to ensure protection against known vulnerabilities.
Implement network-level security measures to detect and block malicious traffic targeting the file repository.

Patching and Updates

Stay informed about security updates released by Moodle and promptly apply patches to address security weaknesses and protect your system.