CVE-2021-21605

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier allows users with Agent/Configure permission to choose agent names that cause Jenkins to override unrelated config.xml files. If the global config.xml file is replaced, Jenkins will start up with unsafe legacy defaults after a restart.

Jenkins 2.275, LTS 2.263.2 ensures that agent names are considered valid names for items to prevent this problem.

In case of problems, this change can be reverted by setting the Java system property jenkins.model.Nodes.enforceNameRestrictions to false.

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-2021-21605 has a CVSS score of 8.0 (High). The vector is network-reachable, low privileges required, and user interaction required. 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-2021-21605? CVE-2021-21605 is a high-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-2021-21605? CVE-2021-21605 has a CVSS score of 8.0 (High). 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-2021-21605? org.jenkins-ci.main:jenkins-core (maven) versions < 2.263.2 is affected.
4. Is there a fix for CVE-2021-21605? Yes. CVE-2021-21605 is fixed in 2.263.2, 2.275. Upgrade to this version or later.
5. Is CVE-2021-21605 exploitable, and should I be worried? Whether CVE-2021-21605 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-2021-21605 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-2021-21605?
   • 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