CVE-2021-43956 Explained : Impact and Mitigation

Fisheye and Crucible versions before 4.8.9 by Atlassian are vulnerable to a jQuery deserialize library issue allowing remote attackers to inject arbitrary HTML and JavaScript.

Understanding CVE-2021-43956

What is CVE-2021-43956?

The vulnerability in Fisheye and Crucible versions prior to 4.8.9 enables remote attackers to inject malicious HTML and JavaScript through a prototype pollution flaw.

The Impact of CVE-2021-43956

This vulnerability, categorized as Cross Site Scripting (XSS), can be exploited by attackers to execute arbitrary code and perform various malicious activities.

Technical Details of CVE-2021-43956

Vulnerability Description

A jQuery deserialize library vulnerability in Fisheye and Crucible versions before 4.8.9 permits remote attackers to insert unauthorized HTML and JavaScript, posing a significant security risk.

Affected Systems and Versions

Product: Fisheye
Vendor: Atlassian
Versions Affected: < 4.8.9 (unspecified/custom)
Product: Crucible
Vendor: Atlassian
Versions Affected: < 4.8.9 (unspecified/custom)

Exploitation Mechanism

The security flaw arises due to inadequate input validation in the jQuery deserialize library, allowing threat actors to manipulate the application's behavior and inject malicious scripts.

Mitigation and Prevention

Immediate Steps to Take

Upgrade Fisheye and Crucible to version 4.8.9 or later to address the vulnerability.
Implement strict input validation to prevent arbitrary code execution.
Monitor network traffic for any suspicious activities that might indicate an exploit attempt.

Long-Term Security Practices

Regularly conduct security assessments and code reviews to identify and remediate potential vulnerabilities.
Educate developers and administrators on secure coding practices and security best practices to prevent future XSS incidents.

Patching and Updates

Apply security patches provided by Atlassian promptly to mitigate the risks associated with the CVE-2021-43956 vulnerability.