In all versions of GitLab CE/EE since version 10.6, a project export leaks the external webhook token value which may allow access to the project which it was exported from.
https://hackerone.com/reports/698068
https://gitlab.com/gitlab-org/gitlab/-/issues/33734
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39898.json