CVE-2021-32821 Explained : Impact and Mitigation

A detailed overview of the Regular expression Denial of Service vulnerability in MooTools affecting all known versions.

Understanding CVE-2021-32821

This CVE involves a vulnerability in MooTools, a collection of JavaScript utilities, specifically in the CSS selector parser susceptible to Regular Expression Denial of Service (ReDoS) attacks.

What is CVE-2021-32821?

MooTools, including version 1.6.0, is impacted by a ReDoS vulnerability due to the CSS selector parser. Attackers can exploit this by injecting strings into CSS selectors at runtime.

The Impact of CVE-2021-32821

This vulnerability could lead to a scenario where an attacker causes a denial of service by exploiting the CSS selector parser, potentially affecting the availability of the system.

Technical Details of CVE-2021-32821

In this section, we will delve into the specifics of the vulnerability, the affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability in the CSS selector parser of MooTools allows for ReDoS attacks, enabling threat actors to disrupt system availability.

Affected Systems and Versions

Vendor: MooTools
Product: MooTools Core
Affected Version: 1.6.0

Exploitation Mechanism

Attackers inject malicious strings into CSS selectors, triggering a ReDoS scenario that could potentially impact system availability.

Mitigation and Prevention

To address CVE-2021-32821, immediate steps should be taken to mitigate risks, along with implementing long-term security practices and applying necessary patches and updates.

Immediate Steps to Take

Ensure that inputs are sanitized, monitor and restrict the use of user-controlled data, and implement security controls to prevent CSS selector injection.

Long-Term Security Practices

Regular security audits, developer training on secure coding practices, and continuous monitoring can help prevent similar vulnerabilities in the future.

Patching and Updates

While there are no available patches at the moment, organizations should stay updated with vendor releases and security advisories to apply fixes promptly.