The Active Admin (aka activeadmin) framework before 3.2.2 for Ruby on Rails allows stored XSS in certain situations where users can create entities (to be later edited in forms) with arbitrary names, aka a "dynamic form legends" issue. 4.0.0.beta7 is also a fixed version.
https://rubygems.org/gems/activeadmin/versions/3.2.2
https://github.com/activeadmin/activeadmin/security/advisories/GHSA-9mg6-x45v-hcfm
https://github.com/activeadmin/activeadmin/releases/tag/v3.2.2