CVE-2021-22540 : What You Need to Know

This article provides details about CVE-2021-22540, a vulnerability in Dart SDK prior to version 2.12.3 that can lead to an XSS attack via DOM clobbering.

Understanding CVE-2021-22540

This section explores the impact, technical details, and mitigation strategies related to CVE-2021-22540.

What is CVE-2021-22540?

CVE-2021-22540 is a vulnerability in the Dart SDK versions before 2.12.3 that arises from bad validation logic. It allows an attacker to execute cross-site scripting (XSS) attacks through DOM clobbering. The issue originates from the validation logic in dart:html module.

The Impact of CVE-2021-22540

The vulnerability enables threat actors to exploit the XSS loophole via DOM clobbering. Attackers can circumvent proper sanitization during the creation of DOM nodes from text, particularly when encountering template tags.

Technical Details of CVE-2021-22540

This section delves into the specifics of the vulnerability, including its description, affected systems, and exploitation mechanism.

Vulnerability Description

The flaw in the validation logic of Dart SDK versions before 2.12.3 allows attackers to leverage DOM clobbering for executing XSS attacks. Insufficient sanitization of template tags in dart:html module exacerbates the issue.

Affected Systems and Versions

The vulnerability impacts Dart SDK version prior to 2.12.3, specifically the stable version. Users running affected versions are at risk of XSS attacks facilitated by DOM clobbering.

Exploitation Mechanism

Threat actors can exploit this vulnerability by crafting malicious payloads that bypass the flawed validation logic in Dart SDK. By manipulating DOM nodes using template tags, attackers can inject and execute malicious scripts.

Mitigation and Prevention

This section outlines immediate steps and long-term practices to safeguard systems against CVE-2021-22540.

Immediate Steps to Take

Users are advised to update their Dart SDK to version 2.12.3 or above to mitigate the vulnerability. Additionally, implementing input validation and output encoding can help prevent XSS attacks.

Long-Term Security Practices

Developers should prioritize secure coding practices, such as input validation, output encoding, and DOM sanitization. Regular security assessments and updates are essential for maintaining a robust defense against XSS vulnerabilities.

Patching and Updates

Google has released patches in Dart SDK version 2.12.3 to address the validation logic issue. Users are urged to apply the latest updates promptly to secure their systems against potential XSS threats.