Deserialization filter bypass in Jenkins Remoting library (CVE-2026-70426)

In Remoting 3384.v60d89463d9e0 and earlier (except 3355.3357.v931d3c992987), the JEP-200 class filter is not applied to classes resolved via a fallback path in the Remoting deserialization implementation. This allows 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 be leveraged to execute code on the Jenkins controller. Affected versions: - Remoting 3384.v60d89463d9e0 and earlier, except 3355.3357.v931d3c992987 - Jenkins 2.575 and earlier - Jenkins LTS 2.568.1 and earlier We recommend updating to: Jenkins 2.576, Jenkins LTS 2.568.2. CVSS ? · our assessment: act_now Reference: https://seclists.org/oss-sec/2026/q3/438 Details: https://vuln.today/cve/CVE-2026-70426