CVE-2021-39935 : What You Need to Know

This CVE-2021-39935 article provides details about a vulnerability found in GitLab versions between 10.5 and 14.5.2, allowing unauthorized external users to perform Server Side Requests via the CI Lint API.

Understanding CVE-2021-39935

CVE-2021-39935 is a vulnerability affecting GitLab versions, potentially enabling Server-side request forgery (SSRF) attacks.

What is CVE-2021-39935?

An issue in GitLab CE/EE versions from 10.5 to 14.5.2 allows unauthorized external users to perform Server Side Requests via the CI Lint API.

The Impact of CVE-2021-39935

This vulnerability has a CVSSv3.1 base score of 6.8 (Medium severity) and high confidentiality impact but does not affect availability or integrity.

Technical Details of CVE-2021-39935

This section delves into the technical specifics of the CVE.

Vulnerability Description

The issue allows unauthorized external users to execute Server-side requests through the CI Lint API in GitLab versions between 10.5 and 14.5.2.

Affected Systems and Versions

GitLab versions >=10.5, <14.3.6
GitLab versions >=14.4, <14.4.4
GitLab versions >=14.5, <14.5.2

Exploitation Mechanism

The vulnerability arises from improper access control in the CI Lint API, enabling external users to trigger Server Side Requests.

Mitigation and Prevention

Learn how to mitigate and prevent potential security risks.

Immediate Steps to Take

Upgrade GitLab to version 14.3.6, 14.4.4, or 14.5.2 to eliminate the vulnerability.
Restrict access to the CI Lint API to authorized users only.

Long-Term Security Practices

Regularly update GitLab to the latest versions to apply security patches.
Conduct security training for developers on secure coding practices.

Patching and Updates

Ensure GitLab is consistently updated to the latest secure versions to stay protected against vulnerabilities.