CVE-2021-22862 : Vulnerability Insights and Analysis

An improper access control vulnerability was identified in GitHub Enterprise Server that allowed an authenticated user with the ability to fork a repository to disclose Actions secrets for the parent repository of the fork. This flaw enabled an arbitrary update to the base reference of a pull request, allowing secrets to be revealed. This issue affected GitHub Enterprise Server version 3.0.0, 3.0.0.rc2, and 3.0.0.rc1, and was reported through the GitHub Bug Bounty program.

Understanding CVE-2021-22862

This CVE describes an improper access control vulnerability in GitHub Enterprise Server, potentially leading to the disclosure of Actions secrets to forks.

What is CVE-2021-22862?

CVE-2021-22862 pertains to a security vulnerability in GitHub Enterprise Server that allowed an authenticated user to expose Actions secrets of the parent repository by manipulating the base reference of a pull request.

The Impact of CVE-2021-22862

The vulnerability could be exploited by an authenticated user to bypass restrictions on Actions secrets in workflows sent from forked repositories, potentially leading to unauthorized access to sensitive information.

Technical Details of CVE-2021-22862

This section provides more in-depth technical insights into the issue.

Vulnerability Description

The vulnerability in GitHub Enterprise Server stemmed from allowing the base reference of a pull request to be amended to an arbitrary SHA or another pull request outside the fork repository, enabling disclosure of Actions secrets.

Affected Systems and Versions

GitHub Enterprise Server versions 3.0.0, 3.0.0.rc2, and 3.0.0.rc1 were impacted by this vulnerability.

Exploitation Mechanism

By manipulating the base reference in a pull request, an authenticated user could bypass restrictions on Actions secrets sent from forked repositories, potentially exposing sensitive data.

Mitigation and Prevention

Learn how to protect your GitHub Enterprise Server deployment from CVE-2021-22862.

Immediate Steps to Take

It is recommended to update GitHub Enterprise Server to version 3.0.1 or newer to address this vulnerability. Additionally, review access controls and audit Actions secrets settings.

Long-Term Security Practices

Implement a secure development pipeline and regularly audit access controls to prevent unauthorized disclosure of sensitive information.

Patching and Updates

Regularly apply security patches and updates provided by GitHub to ensure your instance of GitHub Enterprise Server is secure.