CVE-2021-39894 : Exploit Details and Defense Strategies

This CVE article provides details about a vulnerability in GitLab, affecting versions >=8.0 and <14.3.1.

Understanding CVE-2021-39894

This section delves into the vulnerability present in GitLab, impacting its users.

What is CVE-2021-39894?

In all versions of GitLab CE/EE since version 8.0, there is a DNS rebinding vulnerability in the Fogbugz importer. This flaw can be exploited by attackers for Server-Side Request Forgery attacks.

The Impact of CVE-2021-39894

The vulnerability has a CVSS base score of 5.4 (Medium severity), with low impacts on confidentiality, integrity, and privileges required. The issue lies in the reliance on reverse DNS resolution for security-critical actions in GitLab.

Technical Details of CVE-2021-39894

This section provides a more in-depth look at the technical aspects of the CVE.

Vulnerability Description

Type: Reliance on reverse DNS resolution for security-critical actions

Affected Systems and Versions

Product: GitLab
Vendor: GitLab
Affected Versions: >=8.0, <14.1.7; >=14.2, <14.3.1

Exploitation Mechanism

Attackers can exploit the DNS rebinding vulnerability in GitLab's Fogbugz importer to perform SSRF attacks.

Mitigation and Prevention

Mitigation strategies and preventive measures to address CVE-2021-39894.

Immediate Steps to Take

Update GitLab to versions 14.1.7, 14.2.5, or 14.3.1 to fix the vulnerability

Long-Term Security Practices

Regularly monitor and update software for security patches
Implement strict input validation mechanisms

Patching and Updates

Ensure timely installation of security patches and updates provided by GitLab.