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.
An issue was discovered in OpenStack Keystone before 15.0.1, and 16.0.0. The EC2 API doesn't have a signature TTL check for AWS Signature V4. An attacker can sniff the Authorization header, and then use it to reissue an OpenStack token an unlimited number of times.