CVE-2021-20186 Explained : Impact and Mitigation

A vulnerability was discovered in Moodle versions 3.10.1, 3.9.4, 3.8.7, and 3.5.16 that could lead to stored Cross-Site Scripting (XSS) attacks when the TeX notation filter is enabled.

Understanding CVE-2021-20186

This section will delve into the specifics of CVE-2021-20186.

What is CVE-2021-20186?

The vulnerability in Moodle versions prior to 3.10.1 allowed for the potential risk of stored XSS due to inadequate sanitization of TeX content when the TeX notation filter was activated.

The Impact of CVE-2021-20186

By exploiting this vulnerability, an attacker could inject malicious scripts into Moodle's content, leading to unauthorized access, data theft, and other malicious activities.

Technical Details of CVE-2021-20186

Let's explore the technical aspects of CVE-2021-20186.

Vulnerability Description

The issue stemmed from the insufficient sanitization of TeX content, opening the door for malicious script injection and potential XSS attacks.

Affected Systems and Versions

Moodle versions 3.10.1, 3.9.4, 3.8.7, and 3.5.16 were impacted by this vulnerability if the TeX notation filter was active.

Exploitation Mechanism

Attackers could exploit this flaw by crafting malicious TeX content to bypass existing filters and execute arbitrary scripts within Moodle.

Mitigation and Prevention

Discover how to mitigate and prevent the risks associated with CVE-2021-20186.

Immediate Steps to Take

Users are advised to update their Moodle instances to version 3.10.1 or apply patches provided by Moodle to address the XSS vulnerability.

Long-Term Security Practices

Incorporate robust content filtering mechanisms and regularly update Moodle to mitigate the risk of XSS attacks.

Patching and Updates

Stay informed about security updates from Moodle and promptly apply patches to secure your system against known vulnerabilities.