Jenkins core currently depends on Groovy 2.4.21 (released on November 29, 2020), which is out of date. At the time of this writing, the oldest actively supported Groovy line is 2.5.x, and the latest version of Groovy 2.5.x is is 2.5.17 (released on May 28, 2022). This ticket proposes upgrading Groovy to the latest in the 2.5 series as a step to upgrading to 3.0.x (see JENKINS-51823).

As described in jenkinsci/jenkins#5112 (comment) and jenkinsci/jenkins#5116 (comment), the main concern when upgrading Groovy is ensuring that sandboxed script execution remains secure.