CVE-2022-39321 Explained : Impact and Mitigation

GitHub Actions Runner is the application responsible for executing jobs from GitHub Actions workflows. A vulnerability has been identified in versions prior to 2.296.2, 2.293.1, 2.289.4, 2.285.2, and 2.283.4 that allows an attacker to manipulate Docker commands by escaping environment variables. This CVE poses a risk to jobs using container actions, job containers, or service containers with untrusted user inputs in environment variables.

Understanding CVE-2022-39321

This section provides an overview of the vulnerability, its impact, technical details, and mitigation strategies.

What is CVE-2022-39321?

CVE-2022-39321 is a security vulnerability in GitHub Actions Runner that enables malicious actors to modify Docker command invocations by escaping environment variables. This can lead to unauthorized command execution with elevated privileges.

The Impact of CVE-2022-39321

The impact of this vulnerability is rated as HIGH, with a CVSS v3.1 base score of 8.8. Attackers can exploit this issue to compromise confidentiality, integrity, and availability of affected systems if not addressed promptly.

Technical Details of CVE-2022-39321

Let's delve into the specifics of this vulnerability.

Vulnerability Description

The flaw lies in the logic of how the environment is encoded into Docker commands within GitHub Actions Runner, allowing for direct manipulation by attackers.

Affected Systems and Versions

GitHub Actions Runner versions prior to 2.296.2, 2.293.1, 2.289.4, 2.285.2, and 2.283.4 are impacted by this vulnerability. Systems running these versions are at risk of Docker command escaping.

Exploitation Mechanism

Attackers can exploit this vulnerability by supplying malicious inputs in environment variables, thereby altering Docker command invocations and potentially gaining unauthorized access.

Mitigation and Prevention

It's crucial to implement immediate steps to mitigate the risks associated with CVE-2022-39321.

Immediate Steps to Take

Users are advised to update GitHub Actions Runner to patched versions (2.296.2, 2.293.1, 2.289.4, 2.285.2, 2.283.4) to prevent exploitation of this vulnerability.

Long-Term Security Practices

Incorporate secure coding practices and regular security audits to prevent and detect similar vulnerabilities in the future.

Patching and Updates

GitHub has released patches for both

github.com

and enterprise customers (GHES and GHAE) to address CVE-2022-39321. Users should apply these patches promptly to safeguard their systems.