An issue was discovered in OpenStack Keystone before 15.0.1, and 16.0.0. Any authenticated user can create an EC2 credential for themselves for a project that they have a specified role on, and then perform an update to the credential user and project, allowing them to masquerade as another user. This potentially allows a malicious user to act as the admin on a project another user has the admin role on, which can effectively grant that user global admin privileges.
www.openwall.com/lists/oss-security/2020/05/07/2
bugs.launchpad.net/keystone/+bug/1872733
lists.apache.org/thread.html/re237267da268c690df5e1c6ea6a38a7fc11617725e8049490f58a6fa%40%3Ccommits.druid.apache.org%3E
lists.apache.org/thread.html/re4ffc55cd2f1b55a26e07c83b3c22c3fe4bae6054d000a57fb48d8c2%40%3Ccommits.druid.apache.org%3E
security.openstack.org/ossa/OSSA-2020-004.html
usn.ubuntu.com/4480-1/
www.openwall.com/lists/oss-security/2020/05/06/5