CVE-2021-21423 : Security Advisory and Response

A project generation tool,

projen

, versions >= 0.6.0 and < 0.16.41, is affected by a vulnerability that allows any GitHub user to trigger execution of un-trusted code in the main repository context, potentially leading to unauthorized access to secrets configured in the repository.

Understanding CVE-2021-21423

This vulnerability in projen can be exploited to execute un-trusted code within the main repository, posing a risk of unauthorized activities and access to sensitive information.

What is CVE-2021-21423?

CVE-2021-21423 highlights the exposure of version-control repository to an unauthorized control sphere in projen, enabling potential execution of un-trusted code by any GitHub user.

The Impact of CVE-2021-21423

The impact of this vulnerability includes the risk of unauthorized access to secrets configured in the repository by exploiting the rebuild-bot workflow in projen projects.

Technical Details of CVE-2021-21423

The vulnerability arises due to the rebuild-bot workflow triggered by comments containing

@projen rebuild

on pull requests, executing with a

GITHUB_TOKEN

of the main repository.

Vulnerability Description

The flaw allows untrusted users to access secrets configured on the repository, bypassing branch protection that would typically mitigate such unauthorized access.

Affected Systems and Versions

Versions of projen from >= 0.6.0 to < 0.16.41 are affected by this vulnerability, specifically impacting projects utilizing the

NodeProject

project type.

Exploitation Mechanism

The vulnerability can be exploited by triggering the rebuild-bot workflow with specific comments, allowing execution of un-trusted code in the main repository context.

Mitigation and Prevention

Proper mitigation strategies are essential to prevent exploitation of this vulnerability in projen.

Immediate Steps to Take

Users are advised to update to a version beyond 0.16.41 to mitigate the exposure of untrusted code execution in projen projects.

Long-Term Security Practices

Implement branch protection on default branches to restrict unauthorized access to secrets and sensitive repository configurations in the long term.

Patching and Updates

Regularly check for updates and security patches for projen to ensure that the project is not vulnerable to potential exploits.