A vulnerability was discovered in GitLab versions before 13.1.10, 13.2.8 and 13.3.4. The revocation feature was not revoking all session tokens and one could re-use it to obtain a valid session.
GitLab CE/EE version 13.3 prior to 13.3.4 was vulnerable to an OAuth authorization scope change without user consent in the middle of the authorization flow.