The login method in LoginModule implementations in Apache Geronimo before 2.0.1 does not throw FailedLoginException for failed logins, which allows remote attackers to bypass authentication requirements, deploy arbitrary modules, and gain administrative access by sending a blank username and password with the command line deployer in the deployment module.
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.