CVE-2021-21606

Description

Jenkins provides a feature for jobs to store and track fingerprints of files used during a build. Jenkins 2.274 and earlier, LTS 2.263.1 and earlier provides a REST API to check where a given fingerprint was used by which builds. This endpoint does not fully validate that the provided fingerprint ID is properly formatted before checking for the XML metadata for that fingerprint on the controller file system. This allows attackers with Overall/Read permission to check for the existence of XML files on the controller file system where the relative path can be constructed as 32 characters. Jenkins 2.275, LTS 2.263.2 validates that a fingerprint ID is properly formatted before checking for its existence.

How to fix CVE-2021-21606

To remediate CVE-2021-21606, upgrade the affected package to a fixed version below.

• —upgrade to 2.274.1 or later
• —upgrade to 2.263.2 or later

Is CVE-2021-21606 being exploited?

Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 2.274.1
• from 0, < 2.263.2

CVSS scores

References (4)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-21606
• PATCHgithub.com/jenkinsci/jenkins
• WEBgithub.com/jenkinsci/jenkins/commit/f576b2eb4375f2bb076ce477cee27a946b65f22a
• WEBwww.jenkins.io/security/advisory/2021-01-13/#SECURITY-2023