Information about the starred projects for private user profiles was exposed via the GraphQL API starting from 12.2 via the REST API. This affects GitLab >=12.2 to <13.4.7, >=13.5 to <13.5.5, and >=13.6 to <13.6.2.
https://gitlab.com/gitlab-org/gitlab/-/issues/277337
https://gitlab.com/gitlab-org/cves/-/blob/master/2020/CVE-2020-26415.json