An issue was discovered in Moxa NPort 5110 versions prior to 2.6, NPort 5130/5150 Series versions prior to 3.6, NPort 5200 Series versions prior to 2.8, NPort 5400 Series versions prior to 3.11, NPort 5600 Series versions prior to 3.7, NPort 5100A Series & NPort P5150A versions prior to 1.3, NPort 5200A Series versions prior to 1.3, NPort 5150AI-M12 Series versions prior to 1.2, NPort 5250AI-M12 Series versions prior to 1.2, NPort 5450AI-M12 Series versions prior to 1.2, NPort 5600-8-DT Series versions prior to 2.4, NPort 5600-8-DTL Series versions prior to 2.4, NPort 6x50 Series versions prior to 1.13.11, NPort IA5450A versions prior to v1.4. An attacker can freely use brute force to determine parameters needed to bypass authentication.