OpenStack Keystone 15.0.0 and 16.0.0 is affected by Data Leakage in the list credentials API. Any user with a role on a project is able to list any credentials with the /v3/credentials API when enforce_scope is false. Users with a role on a project are able to view any other users' credentials, which could (for example) leak sign-on information for Time-based One Time Passwords (TOTP). Deployments with enforce_scope set to false are affected. (There will be a slight performance impact for the list credentials API once this issue is fixed.)
https://usn.ubuntu.com/4262-1/
https://security.openstack.org/ossa/OSSA-2019-006.html
https://review.opendev.org/#/c/697731/
https://review.opendev.org/#/c/697611/
https://review.opendev.org/#/c/697355/
https://bugs.launchpad.net/keystone/+bug/1855080