A vulnerability in the CLI of Cisco NX-OS System Software could allow an authenticated, local attacker to perform a command injection attack. The vulnerability is due to insufficient input validation of command arguments to the CLI parser. An attacker could exploit this vulnerability by injecting crafted command arguments into a vulnerable CLI command and gaining unauthorized access to the underlying operating system of the device. An exploit could allow the attacker to execute arbitrary commands at the user's privilege level. On products that support multiple virtual device contexts (VDCs), this vulnerability could allow an attacker to execute commands at the user's privilege level outside the user's environment. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCve99902, CSCvf14879.