DBMail is a mail storage and retrieval daemon that uses SQL databases as its data store. IMAP and POP3 can be used to retrieve mails from the database.
A vulnerability in DBMail's authldap module when used in conjunction with an Active Directory server has been reported by vugluskr. When passing a zero length password to the module, it tries to bind anonymously to the LDAP server. If the LDAP server allows anonymous binds, this bind succeeds and results in a successful authentication to DBMail.
By passing an empty password string to the server, an attacker could be able to log in to any account.
There is no known workaround at this time.
All DBMail users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-mail/dbmail-2.2.9"