CVE-2021-39904 : Exploit Details and Defense Strategies

This CVE article provides detailed information on an Improper Access Control vulnerability in GitLab.

Understanding CVE-2021-39904

This section delves into the impact and technical details of the CVE.

What is CVE-2021-39904?

CVE-2021-39904 is an Improper Access Control vulnerability in the GraphQL API of GitLab versions, allowing specific unauthorized actions.

The Impact of CVE-2021-39904

The vulnerability possesses a CVSS base score of 4.3 (Medium severity) and affects several GitLab versions, enabling unauthorized access.

Technical Details of CVE-2021-39904

Explore the technical aspects and implications of this vulnerability.

Vulnerability Description

The vulnerability allows a Merge Request creator in GitLab to carry out actions even after project owners lock the Merge Request, compromising access control.

Affected Systems and Versions

Affected Product: GitLab
Vulnerable Versions:
=13.1, <14.2.6

=14.3, <14.3.4

=14.4, <14.4.1

Exploitation Mechanism

The vulnerability in GitLab's GraphQL API permits unauthorized users to manipulate Merge Request discussions and suggestions post-locking.

Mitigation and Prevention

Learn how to mitigate the risks posed by CVE-2021-39904.

Immediate Steps to Take

Upgrade GitLab instances to versions 14.2.6, 14.3.4, or 14.4.1, respectively, to eliminate the vulnerability.
Monitor and restrict actions within Merge Requests to prevent unauthorized access.

Long-Term Security Practices

Regularly review and update access control configurations within GitLab to prevent future vulnerabilities.
Conduct security awareness training to educate users on maintaining secure practices.

Patching and Updates

Stay informed about security updates from GitLab and promptly apply patches to address known vulnerabilities.