Jenkins: unvalidated agent name lets a read-only user load and overwrite arbitrary config.xml on the controller

Impact

An HTTP endpoint loads an agent configuration by name without validating the name, so any user holding only Overall/Read can make the controller parse any config.xml on its filesystem as an agent definition and, on save, overwrite an arbitrary config.xml. Overwriting the controller's own configuration files is a credible path to arbitrary code execution as the Jenkins user. On a GPU fleet the Jenkins controller usually holds the credentials that drive image builds, model pushes and cluster deploys, so controller code execution reaches further than the build nodes themselves. Scored 8.8 by the CNA.

Who can reach it

Any authenticated Jenkins user with Overall/Read over the network - no job configuration or admin rights needed.

What to do

Upgrade to the fixed Jenkins weekly and LTS releases named in the 2026-10-28 advisory and restart the controller; the advisory text in this record does not state the fixed version numbers. Controller restart is a short outage for queued builds only, no node drain. Until then, tighten who holds Overall/Read on the controller.

References

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