GitLab EE/CE 8.11 through 12.9.1 allows blocked users to pull/push docker images.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2020-3356
https://about.gitlab.com/releases/categories/releases/
https://about.gitlab.com/releases/2020/03/26/security-release-12-dot-9-dot-1-released/