The c-client library 2000, 2001, or 2004 for PHP before 4.4.4 and 5.x before 5.1.5 do not check the (1) safe_mode or (2) open_basedir functions, and when used in applications that accept user-controlled input for the mailbox argument to the imap_open function, allow remote attackers to obtain access to an IMAP stream data structure and conduct unauthorized IMAP actions.