imap/nntpd.c in the NNTP server (nntpd) for Cyrus IMAPd 2.4.x before 2.4.12 allows remote attackers to bypass authentication by sending an AUTHINFO USER command without sending an additional AUTHINFO PASS command.
http://cyrusimap.org/mediawiki/index.php/Latest_Updates
http://git.cyrusimap.org/cyrus-imapd/commit/?id=77903669e04c9788460561dd0560b9c916519594
http://secunia.com/advisories/46093
http://secunia.com/secunia_research/2011-68
http://securitytracker.com/id?1026363
http://www.debian.org/security/2011/dsa-2318
http://www.mandriva.com/security/advisories?name=MDVSA-2011:149