Due to an insecure direct object reference vulnerability in Gitlab EE/CE affecting all versions from 11.0 prior to 14.8.6, 14.9 prior to 14.9.4, and 14.10 prior to 14.10.1, an endpoint may reveal the issue title to a user who crafted an API call with the ID of the issue from a public project that restricts access to issue only to project members.
CWE-639