OpenStack Keystone Essex before 2012.1.2 and Folsom before folsom-3 does not properly handle authorization tokens for disabled tenants, which allows remote authenticated users to access the tenant's resources by requesting a token for the tenant.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.