Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not escape button labels in the Jenkins UI.
This results in a cross-site scripting vulnerability exploitable by attackers with the ability to control button labels. An example of buttons with a user-controlled label are the buttons of the Pipeline input
step.
Jenkins 2.275, LTS 2.263.2 escapes button labels in the Jenkins UI.