CVE-2021-36398 : Security Advisory and Response

A stored XSS risk was identified in Moodle, where ID numbers displayed in the web service token list required additional sanitizing to prevent exploitation.

Understanding CVE-2021-36398

This section delves into the details of CVE-2021-36398, highlighting the vulnerability, impact, and technical aspects.

What is CVE-2021-36398?

CVE-2021-36398 refers to a stored XSS vulnerability in Moodle, specifically related to the lack of adequate sanitization of ID numbers displayed in the web service token list. This flaw could potentially allow malicious actors to execute arbitrary scripts in the context of a user's session.

The Impact of CVE-2021-36398

The impact of this vulnerability is significant as it could lead to unauthorized access, data theft, or complete system compromise. Exploitation of this security flaw can result in severe consequences for affected systems and users.

Technical Details of CVE-2021-36398

Explore the technical aspects of CVE-2021-36398 to better understand its implications and how it can be mitigated.

Vulnerability Description

The vulnerability arises from the failure to properly sanitize ID numbers in the web service token list, making it vulnerable to stored XSS attacks. Attackers can exploit this weakness to inject malicious scripts, leading to unauthorized actions within the application.

Affected Systems and Versions

The affected system is Moodle version 3.11, where the vulnerability exposes systems running this version to the risk of stored XSS attacks. Users of this version should be vigilant and apply necessary patches.

Exploitation Mechanism

By leveraging the lack of sanitization in the web service token list, attackers can manipulate ID numbers to inject malicious scripts. These scripts can then execute within the user's session, potentially leading to the compromise of sensitive information.

Mitigation and Prevention

Understand the steps required to mitigate the risks posed by CVE-2021-36398 and prevent exploitation of this vulnerability.

Immediate Steps to Take

Users and administrators are advised to apply security patches provided by Moodle promptly. Additionally, implementing adequate input validation and output encoding can help prevent XSS attacks.

Long-Term Security Practices

Incorporate secure coding practices within development processes to avoid similar vulnerabilities in the future. Regular security audits and testing can also aid in identifying and addressing potential security flaws.

Patching and Updates

Regularly monitor for security updates from Moodle and apply patches as soon as they are released to protect systems from known vulnerabilities.