Command injection vulnerability in Citrix NetScaler ADC and NetScaler Gateway 11.0 before build 70.16, 11.1 before build 55.13, and 12.0 before build 53.13; and the NetScaler Load Balancing instance distributed with NetScaler SD-WAN/CloudBridge 4000, 4100, 5000 and 5100 WAN Optimization Edition 9.3.0 allows remote attackers to execute a system command or read arbitrary files via an SSH login prompt.