High [CVE-2026-70426] Arbitrary code execution via deserialization filter bypass

In Remoting 3384.v60d89463d9e0 and earlier, except 3355.3357.v931d3c992987, included in Jenkins 2.575 and earlier, LTS 2.568.1 and earlier, the JEP-200 class filter is not applied to classes resolved via a fallback path in the Remoting deserialization implementation, allowing agent processes, code running on agents, and attackers with Agent/Connect permission to bypass the JEP-200 deserialization filter for classes on the Jenkins core classpath.

Successful exploitation could lead to arbitrary code execution on the Jenkins controller. This Important flaw in Jenkins Remoting allows authenticated attackers or compromised agent processes to execute arbitrary code on the Jenkins controller.

The vulnerability stems from an incomplete deserialization filter bypass, enabling full compromise of the Jenkins environment. This impacts Red Hat OpenShift Developer Tools & Services deployments that utilize Jenkins agents, as it could lead to unauthorized control over the build and deployment infrastructure.

Agent traffic in Red Hat OpenShift Developer Tools is restricted to a cluster's internal pod network which reduces the attack vector from Network to Adjacent. Red Hat severity: Important — CVSS 8.3 (CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H).

Weakness: CWE-502.