The contrib.auth.middleware.RemoteUserMiddleware middleware in Django before 1.4.14, 1.5.x before 1.5.9, 1.6.x before 1.6.6, and 1.7 before release candidate 3, when using the contrib.auth.backends.RemoteUserBackend backend, allows remote authenticated users to hijack web sessions via vectors related to the REMOTE_USER header. Branches prior to 1.4.x are unsupported and might be vulnerable as well.
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.