The (1) Catapult DNP3 I/O driver before 7.2.0.60 and the (2) GE Intelligent Platforms Proficy DNP3 I/O driver before 7.20k, as used in DNPDrv.exe (aka the DNP master station server) in GE Intelligent Platforms Proficy HMI/SCADA - CIMPLICITY and iFIX, allow remote attackers to cause a denial of service (infinite loop) via a crafted DNP3 TCP packet.