CVE-2021-21616 Explained : Impact and Mitigation

Jenkins Active Choices Plugin 2.5.2 and earlier versions are affected by a stored cross-site scripting (XSS) vulnerability due to improper escaping of reference parameter values. Attackers with Job/Configure permission can exploit this issue.

Understanding CVE-2021-21616

This CVE affects the Jenkins Active Choices Plugin versions up to 2.5.2, leaving them vulnerable to stored XSS attacks.

What is CVE-2021-21616?

CVE-2021-21616 is a security vulnerability in Jenkins Active Choices Plugin that allows attackers with permission to create or configure jobs to execute malicious scripts through stored XSS.

The Impact of CVE-2021-21616

The vulnerability could be exploited by attackers to inject and execute malicious scripts in the context of the affected Jenkins application, potentially leading to unauthorized data access or system compromise.

Technical Details of CVE-2021-21616

The technical details of CVE-2021-21616 include:

Vulnerability Description

Jenkins Active Choices Plugin 2.5.2 and earlier versions improperly handle reference parameter values, enabling stored cross-site scripting attacks.

Affected Systems and Versions

The affected system includes Jenkins Active Choices Plugin up to version 2.5.2.

Exploitation Mechanism

Exploitation of this vulnerability involves submission of crafted input by authenticated attackers with Job/Configure permission, leading to script execution in the context of the application.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-21616, consider the following steps:

Immediate Steps to Take

Update the Jenkins Active Choices Plugin to a non-vulnerable version.
Apply security best practices to limit permissions and access levels within Jenkins.

Long-Term Security Practices

Regularly monitor and patch Jenkins plugins for security updates.
Provide security awareness training to users to prevent the execution of malicious scripts.

Patching and Updates

Ensure timely application of security patches and updates for the Jenkins Active Choices Plugin to address known vulnerabilities.