Multiple buffer overflows in PHP before 5.2.1 allow attackers to cause a denial of service and possibly execute arbitrary code via unspecified vectors in the (1) session, (2) zip, (3) imap, and (4) sqlite extensions; (5) stream filters; and the (6) str_replace, (7) mail, (8) ibase_delete_user, (9) ibase_add_user, and (10) ibase_modify_user functions.  NOTE: vector 6 might actually be an integer overflow (CVE-2007-1885).  NOTE: as of 20070411, vector (3) might involve the imap_mail_compose function (CVE-2007-1825).