Lack of type validation in agent related REST API in Jenkins
Date: 2022-05
Affected: maven/org.jenkins-ci.main:jenkins-core, maven/org.jenkins-ci.main:jenkins-core
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2021-21639
CWE: CWE-20
CVSS: 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N)

Jenkins 2.286 and earlier, LTS 2.277.1 and earlier does not validate the type of object created after loading the data submitted to the `config.xml` REST API endpoint of a node. This allows attackers with Computer/Configure permission to replace a node with one of a different type. Jenkins 2.287, LTS 2.277.2 validates the type of object created and rejects objects of unexpected types.


Mitigations:

Architectural layers (MAESTRO):