Jenkins: attacker-controlled config.xml deserialization allows user impersonation and code execution

Impact

An attacker who can submit a config.xml gets Jenkins to deserialize arbitrary types from core or any installed plugin, in a form that then handles HTTP requests on its own. That yields impersonation of any Jenkins user - including administrators - which reaches the Script Console and therefore arbitrary code execution on the controller, or arbitrary file reads from it. A Jenkins controller in a GPU shop usually holds registry push credentials, kubeconfigs for the training clusters, and signing or cloud keys, so controller compromise is a straight path into the image supply chain feeding every GPU node. Build agents inherit whatever the controller tells them to run.

Who can reach it

Remote attacker with a Jenkins account that permits a config.xml submission (CVSS PR:L - low-privilege authenticated). No user interaction and no access to the build agents required.

What to do

Upgrade past Jenkins 2.567 (weekly) or LTS 2.555.2 per the 2026-06-10 advisory (SECURITY-3707); for OpenShift Developer Tools and Services 4.12 and 4.15 through 4.18, apply RHSA-2026:60239, 60246, 60247 or 60250. Cost is a controller restart - queued builds pause and agents reconnect; running builds are lost unless drained first. No GPU node maintenance. Treat any credential stored on the controller as suspect if you find evidence of exploitation.

References

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