CVE-2021-35043 : Security Advisory and Response

OWASP AntiSamy before version 1.6.4 is vulnerable to cross-site scripting (XSS) attacks through HTML attributes when using the HTML output serializer. Notably, this vulnerability allows XSS via HTML attributes, but not through XHTML. An attacker can exploit this by using a javascript: URL with &#00058 as a replacement for the : character.

Understanding CVE-2021-35043

This section provides insights into the nature and impact of the CVE-2021-35043 vulnerability.

What is CVE-2021-35043?

OWASP AntiSamy before 1.6.4 permits XSS attacks through HTML attributes, excluding XHTML, enabling malicious actors to execute scripts using crafted URLs.

The Impact of CVE-2021-35043

The vulnerability poses a significant risk to web applications, potentially leading to unauthorized script execution, data theft, and other forms of XSS-based attacks.

Technical Details of CVE-2021-35043

Delve deeper into the technical aspects of the CVE-2021-35043 vulnerability to better understand its implications and scope.

Vulnerability Description

The issue in OWASP AntiSamy before 1.6.4 allows attackers to execute XSS attacks by leveraging HTML attributes, presenting a critical security concern for web applications.

Affected Systems and Versions

All versions of OWASP AntiSamy before 1.6.4 are impacted by this vulnerability, highlighting the widespread risk across various systems utilizing this component.

Exploitation Mechanism

By crafting a javascript: URL with &#00058 to replace the : character, threat actors can exploit this flaw to execute malicious scripts within the context of vulnerable web applications.

Mitigation and Prevention

Explore the measures necessary to mitigate the risks associated with CVE-2021-35043 and prevent potential exploitation scenarios.

Immediate Steps to Take

Immediate steps include updating OWASP AntiSamy to version 1.6.4 or newer to address the XSS vulnerability and enhance overall security posture.

Long-Term Security Practices

Implementing secure coding practices, regular security assessments, and staying informed about the latest CVE disclosures are essential for maintaining robust security.

Patching and Updates

Frequent updates and patch management are crucial to address vulnerabilities promptly and ensure the resilience of web applications against evolving threats.