CVE-2021-21694
First published: Thu Nov 04 2021(Updated: )
The agent-to-controller security subsystem limits which files on the Jenkins controller can be accessed by agent processes. Multiple vulnerabilities in the file path filtering implementation of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier allow agent processes to read and write arbitrary files on the Jenkins controller file system, and obtain some information about Jenkins controller file systems. SECURITY-2541 / CVE-2021-21694: `FilePath#toURI`, `FilePath#hasSymlink`, `FilePath#absolutize`, `FilePath#isDescendant`, and `FilePath#get*DiskSpace` do not check any permissions. We expect that most of these vulnerabilities have been present since [SECURITY-144 was addressed in the 2014-10-30 security advisory](https://www.jenkins.io/security/advisory/2014-10-30/). Jenkins 2.319, LTS 2.303.3 addresses these security vulnerabilities. SECURITY-2541 / CVE-2021-21694: `FilePath#toURI`, `FilePath#hasSymlink`, `FilePath#absolutize`, `FilePath#isDescendant` check stat permission. `FilePath#get*DiskSpace` methods are no longer allowed to be executed by an agent. As some common operations are now newly subject to access control, it is expected that plugins sending commands from agents to the controller may start failing. Additionally, the newly introduced path canonicalization means that instances using a custom builds directory ([Java system property jenkins.model.Jenkins.buildsDir](https://www.jenkins.io/doc/book/managing/system-properties/#jenkins-model-jenkins-buildsdir)) or partitioning `JENKINS_HOME` using symbolic links may fail access control checks. See [the documentation](https://www.jenkins.io/doc/book/security/controller-isolation/agent-to-controller/#file-access-rules) for how to customize the configuration in case of problems. If you are unable to immediately upgrade to Jenkins 2.319, LTS 2.303.3, you can install the [Remoting Security Workaround Plugin](https://www.jenkins.io/redirect/remoting-security-workaround/). It will prevent all agent-to-controller file access using `FilePath` APIs. Because it is more restrictive than Jenkins 2.319, LTS 2.303.3, more plugins are incompatible with it. Make sure to read the plugin documentation before installing it.
Credit: jenkinsci-cert@googlegroups.com jenkinsci-cert@googlegroups.com jenkinsci-cert@googlegroups.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Jenkins Jenkins | <2.303.3 | |
| Jenkins Jenkins | <2.319 | |
| redhat/jenkins | <2.319 | 2.319 |
| redhat/jenkins LTS | <2.303.3 | 2.303.3 |
| maven/org.jenkins-ci.main:jenkins-core | <=2.303.2 | 2.303.3 |
| maven/org.jenkins-ci.main:jenkins-core | >=2.304<=2.318 | 2.319 |
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Reference Links
- https://nvd.nist.gov/vuln/detail/CVE-2021-21694
- https://www.jenkins.io/security/advisory/2021-11-04/#SECURITY-2455
- https://github.com/jenkinsci/jenkins/commit/104c751d907919dd53f5090f84d53c671a66457b
- https://github.com/jenkinsci/jenkins/commit/5a245e42979abe4a26d41727c839521e36cedd74
- https://github.com/jenkinsci/jenkins/commit/63cde2daadc705edf086f2213b48c8c547f98358
- https://github.com/advisories/GHSA-pgj6-jmj5-wqfx (Advisory)
- https://access.redhat.com/errata/RHSA-2021:4833
- https://access.redhat.com/errata/RHSA-2021:4829
- https://access.redhat.com/errata/RHSA-2021:4801
- https://access.redhat.com/errata/RHSA-2021:4799
- https://access.redhat.com/errata/RHSA-2021:4827
- https://access.redhat.com/security/cve/cve-2021-21694
- https://bugzilla.redhat.com/show_bug.cgi?id=2020342
Frequently Asked Questions
What is CVE-2021-21694?
CVE-2021-21694 is a vulnerability that affects Jenkins versions 2.318 and earlier, as well as LTS 2.303.2 and earlier. It allows unauthorized access to file paths and does not check permissions.
What are the affected software versions?
Jenkins versions 2.318 and earlier, and LTS 2.303.2 and earlier are affected by CVE-2021-21694.
What is the severity of CVE-2021-21694?
CVE-2021-21694 has a severity rating of 9.8 (critical).
How can I fix CVE-2021-21694?
To fix CVE-2021-21694, it is recommended to update Jenkins to version 2.319 or LTS 2.303.3, which include the necessary security patches.
Where can I find more information about CVE-2021-21694?
More information about CVE-2021-21694 can be found in the Jenkins security advisory: https://www.jenkins.io/security/advisory/2021-11-04/#SECURITY-2455
- agent/author
- agent/description
- agent/event
- agent/first-publish-date
- agent/last-modified-date
- agent/references
- agent/severity
- agent/softwarecombine
- agent/tags
- agent/type
- agent/weakness
- collector/github-advisory
- alias/GHSA-pgj6-jmj5-wqfx
- alias/CVE-2021-21694
- collector/github-advisory-latest
- collector/nvd-api
- collector/nvd-cve
- collector/nvd-index
- collector/redhat-bugzilla
- source/Red Hat
- agent/software-canonical-lookup
- package-manager/maven
- vendor/jenkins
- canonical/jenkins jenkins
- package-manager/redhat