The server driver (srv.sys) in Microsoft Windows NT 4.0, 2000, XP, and Server 2003 allows remote attackers to cause a denial of service (system crash) via an SMB_COM_TRANSACTION SMB message that contains a string without null character termination, which leads to a NULL dereference in the ExecuteTransaction function, possibly related to an "SMB PIPE," aka the "Mailslot DOS" vulnerability.  NOTE: the name "Mailslot DOS" was derived from incomplete initial research; the vulnerability is not associated with a mailslot.