CVE-2021-21697: Critical severity jenkins lts vulnerability
Agents are allowed some limited access to files on the Jenkins controller file system. The directories agents are allowed to access in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier include the directories storing build-related information, intended to allow agents to store build-related metadata during build execution. As a consequence, this allows any agent to read and write the contents of any build directory stored in Jenkins with very few restrictions (build.xml and some Pipeline-related metadata).
Jenkins 2.319, LTS 2.303.3 prevents agents from accessing contents of build directories unless it’s for builds currently running on the agent attempting to access the directory.
Update Pipeline: Nodes and Processes to version 2.40 or newer for Jenkins to associate Pipeline node blocks with the agent they’re running on for this fix.
If you are unable to immediately upgrade to Jenkins 2.319, LTS 2.303.3, you can install the Remoting Security Workaround Plugin. 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.
Other sources
Agents are allowed some limited access to files on the Jenkins controller file system. The directories agents are allowed to access in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier include the directories storing build-related information, intended to allow agents to store build-related metadata during build execution. As a consequence, this allows any agent to read and write the contents of any build directory stored in Jenkins with very few restrictions (build.xml and some Pipeline-related metadata).
— Red Hat
Jenkins 2.318 and earlier, LTS 2.303.2 and earlier allows any agent to read and write the contents of any build directory stored in Jenkins with very few restrictions.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the vulnerability ID?
The vulnerability ID is CVE-2021-21697.
What is the severity of CVE-2021-21697?
The severity of CVE-2021-21697 is critical (9.1).
Which versions of Jenkins are affected by CVE-2021-21697?
Jenkins 2.318 and earlier, LTS 2.303.2 and earlier are affected by CVE-2021-21697.
How can I fix CVE-2021-21697?
To fix CVE-2021-21697, upgrade to Jenkins 2.319 or Jenkins LTS 2.303.3.
Where can I find more information about CVE-2021-21697?
You can find more information about CVE-2021-21697 on the Open Wall website, the Jenkins security advisory, and the Red Hat website.