CVE-2021-21609 : Exploit Details and Defense Strategies

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier versions are affected by CVE-2021-21609. This vulnerability allows attackers without Overall/Read permission to access certain URLs as if they had the permission.

Understanding CVE-2021-21609

This CVE affects Jenkins versions 2.274 and earlier, LTS 2.263.1 and earlier, impacting the authorization mechanism of the platform.

What is CVE-2021-21609?

CVE-2021-21609 is a security vulnerability in Jenkins that incorrectly matches requested URLs to the list of always accessible paths, enabling unauthorized access to certain URLs.

The Impact of CVE-2021-21609

The vulnerability allows attackers without Overall/Read permission to gain access to restricted URLs, potentially leading to unauthorized information exposure or data manipulation.

Technical Details of CVE-2021-21609

The technical details of CVE-2021-21609 include:

Vulnerability Description

Jenkins versions 2.274 and earlier, LTS 2.263.1 and earlier do not accurately match requested URLs, allowing unauthorized access.

Affected Systems and Versions

Jenkins 2.274 and earlier
LTS 2.263.1 and earlier

Exploitation Mechanism

Attackers exploit this vulnerability by accessing URLs that should be restricted, bypassing the intended authorization checks.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-21609, follow these security measures:

Immediate Steps to Take

Upgrade Jenkins to a non-vulnerable version
Implement least privilege access control

Long-Term Security Practices

Regularly review and update Jenkins security configurations
Conduct security training for users on access control best practices

Patching and Updates

Apply patches released by Jenkins project to address the vulnerability and enhance the security of Jenkins installations.