Jenkins Pipeline Remote Loader Plugin 1.4 and earlier provided a custom whitelist for script security that allowed attackers to invoke arbitrary methods, bypassing typical sandbox protection.
https://jenkins.io/security/advisory/2019-05-31/#SECURITY-921
https://access.redhat.com/errata/RHSA-2019:1636
https://access.redhat.com/errata/RHBA-2019:1605