Jenkins 2.367 through 2.369 (both inclusive) does not escape tooltips of the l:helpIcon UI component used for some help icons on the Jenkins web UI, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers able to control tooltips for this component.
As of publication, the Jenkins security team is unaware of any exploitable help icon/tooltip in Jenkins core or plugins published by the Jenkins project. The vast majority of help icons use the l:help component instead of l:helpIcon. The few known instances of l:helpIcon do not have user-controllable tooltip contents.