CVE-2021-21603 : Security Advisory and Response

This CVE-2021-21603 impacts Jenkins versions 2.274 and earlier, LTS 2.263.1, due to a cross-site scripting vulnerability in the notification bar response contents.

Understanding CVE-2021-21603

This CVE affects Jenkins, exposing users to potential cross-site scripting attacks.

What is CVE-2021-21603?

Jenkins versions 2.274 and earlier, LTS 2.263.1, are vulnerable to cross-site scripting (XSS) due to unescaped notification bar response contents.

The Impact of CVE-2021-21603

An attacker could exploit this vulnerability to execute malicious scripts in the context of a user's browser, potentially leading to data theft or unauthorized actions.

Technical Details of CVE-2021-21603

Jenkins versions 2.274 and earlier, LTS 2.263.1 are prone to XSS attacks due to unescaped notification bar responses.

Vulnerability Description

The lack of escaping in notification bar responses allows attackers to inject malicious scripts, compromising user data and system integrity.

Affected Systems and Versions

Affected versions: Jenkins 2.274 and earlier, LTS 2.263.1

Exploitation Mechanism

Exploiting this vulnerability involves injecting malicious scripts via the notification bar responses to execute unauthorized actions.

Mitigation and Prevention

To safeguard your system against CVE-2021-21603, follow these security measures:

Immediate Steps to Take

Upgrade Jenkins to a patched version that addresses the XSS vulnerability.
Implement content security policies to mitigate XSS risks.

Long-Term Security Practices

Regularly update Jenkins to the latest stable versions to prevent known vulnerabilities.
Educate users about safe browsing habits and potential XSS risks.

Patching and Updates

Stay informed about security advisories from Jenkins and apply patches promptly to ensure a secure environment.