When I inquired about how to report security issues to the Dataverse project, I was directed to the Contributing document in the GitHub repo:
https://github.com/IQSS/dataverse/blob/develop/CONTRIBUTING.md
Other good places for this information might be the Contact page of dataverse.org:
https://dataverse.org/contact
or on the front page of the guides, perhaps under Other Resources / Support:
http://guides.dataverse.org/en/latest/