The login form in Roundcube Webmail before 0.5.1 does not properly handle a correctly authenticated but unintended login attempt, which makes it easier for remote authenticated users to obtain sensitive information by arranging for a victim to login to the attacker's account and then compose an e-mail message, related to a "login CSRF" issue.
https://exchange.xforce.ibmcloud.com/vulnerabilities/66815
http://trac.roundcube.net/wiki/Changelog
http://trac.roundcube.net/changeset/4490
http://openwall.com/lists/oss-security/2011/04/04/50