CVE-2021-21688 : Security Advisory and Response

A security vulnerability, identified as CVE-2021-21688, has been discovered in Jenkins, impacting versions 2.318 and earlier, as well as LTS 2.303.2 and earlier. This vulnerability could allow users to gain unrestricted read access through specific operations.

Understanding CVE-2021-21688

This section delves into the details surrounding CVE-2021-21688.

What is CVE-2021-21688?

The security flaw, designated as CVE-2021-21688, affects the agent-to-controller security check FilePath#reading(FileVisitor) in Jenkins. It exists in versions 2.318 and earlier, as well as LTS 2.303.2 and earlier. The vulnerability permits users to obtain unrestricted read access using certain operations such as creating archives and FilePath#copyRecursiveTo.

The Impact of CVE-2021-21688

The impact of CVE-2021-21688 is considerable, as it allows malicious actors to exploit the vulnerability and gain unrestricted read access, potentially compromising the confidentiality of sensitive information.

Technical Details of CVE-2021-21688

This portion outlines the technical specifics of CVE-2021-21688.

Vulnerability Description

The security flaw arises from the FilePath#reading(FileVisitor) security check in Jenkins versions 2.318 and earlier, as well as LTS 2.303.2 and earlier. This flaw facilitates users to perform certain operations and access information without proper authorization, posing a significant security risk.

Affected Systems and Versions

Jenkins versions 2.318 and earlier, along with LTS 2.303.2 and earlier, are impacted by CVE-2021-21688. Users utilizing these versions are urged to take immediate action to address this vulnerability.

Exploitation Mechanism

Malicious actors can exploit this vulnerability by leveraging certain operations, including creating archives and FilePath#copyRecursiveTo, to gain unrestricted read access and potentially compromise the affected systems.

Mitigation and Prevention

In this segment, strategies to mitigate and prevent the exploitation of CVE-2021-21688 are discussed.

Immediate Steps to Take

To mitigate the risks associated with CVE-2021-21688, users are advised to update Jenkins to a patched version that addresses this security vulnerability. Additionally, enforcing least privilege access controls can help limit the impact of such vulnerabilities.

Long-Term Security Practices

Implementing a robust security posture, conducting regular security assessments, and staying abreast of security updates for Jenkins are crucial long-term practices to enhance the overall security of systems and prevent vulnerabilities like CVE-2021-21688.

Patching and Updates

Regularly updating Jenkins to the latest versions, especially those containing security patches, is essential to protect against known vulnerabilities and ensure the security of the respective systems.