The DNP Master Driver in Software Toolbox TOP Server before 5.12.140.0 allows remote attackers to cause a denial of service (master-station infinite loop) via crafted DNP3 packets to TCP port 20000 and allows physically proximate attackers to cause a denial of service (master-station infinite loop) via crafted input over a serial line.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2013-2743
http://support.softwaretoolbox.com/app/answers/detail/a_id/3014