CVE-2021-21606

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.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2021-21606 has a CVSS score of 4.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.263.2, 2.275); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2021-21606? CVE-2021-21606 is a medium-severity improper input validation vulnerability in org.jenkins-ci.main:jenkins-core (maven), affecting versions < 2.263.2. It is fixed in 2.263.2, 2.275. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2021-21606? CVE-2021-21606 has a CVSS score of 4.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of org.jenkins-ci.main:jenkins-core are affected by CVE-2021-21606? org.jenkins-ci.main:jenkins-core (maven) versions < 2.263.2 is affected.
4. Is there a fix for CVE-2021-21606? Yes. CVE-2021-21606 is fixed in 2.263.2, 2.275. Upgrade to this version or later.
5. Is CVE-2021-21606 exploitable, and should I be worried? Whether CVE-2021-21606 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-21606 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-21606?
   • Upgrade org.jenkins-ci.main:jenkins-core to 2.263.2 or later
   • Upgrade org.jenkins-ci.main:jenkins-core to 2.275 or later

Other vulnerabilities in org.jenkins-ci.main:jenkins-core