CVE-2021-29434 : Exploit Details and Defense Strategies

A detailed analysis of CVE-2021-29434, a vulnerability in Wagtail affecting versions <= 2.11.6 and >= 2.12, <= 2.12.3.

Understanding CVE-2021-29434

This section delves into the impact, technical details, and mitigation strategies related to CVE-2021-29434.

What is CVE-2021-29434?

In Wagtail versions <= 2.11.6 and >= 2.12, <= 2.12.3, a vulnerability exists where the system does not apply server-side checks on link URLs in rich text fields within the admin interface. This allows malicious users with admin access to craft POST requests containing

javascript:

URLs with arbitrary code.

The Impact of CVE-2021-29434

The vulnerability's CVSS v3.1 score is 6.1, categorizing it as of medium severity with high confidentiality and integrity impacts. However, exploitation requires high privileges and user interaction.

Technical Details of CVE-2021-29434

This section provides insight into the specific aspects of the vulnerability.

Vulnerability Description

Wagtail fails to validate the protocol of link URLs in rich text fields, enabling potential Cross-site Scripting (XSS) attacks through crafted

javascript:

URLs.

Affected Systems and Versions

Systems with Wagtail versions <= 2.11.6 and >= 2.12, <= 2.12.3 are susceptible to this vulnerability.

Exploitation Mechanism

Malicious users with admin access can exploit this flaw by inserting JavaScript code within

javascript:

URLs in rich text fields.

Mitigation and Prevention

To safeguard your system, follow these immediate steps and long-term security best practices.

Immediate Steps to Take

Users should update Wagtail to patched versions 2.11.7 or 2.12.4, and ensure that only trusted individuals have admin access.

Long-Term Security Practices

Implement strict input validation, conduct regular security audits, and educate staff on safe usage practices.

Patching and Updates

Regularly apply security patches and stay informed about security advisories to promptly address any vulnerabilities.