A vulnerability in the configuration of the Pluggable Authentication Module (PAM) used in Cisco Firepower Threat Defense (FTD) Software, Cisco Firepower Management Center (FMC) Software, and Cisco FXOS Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper resource management in the context of user session management. An attacker could exploit this vulnerability by connecting to an affected system and performing many simultaneous successful Secure Shell (SSH) logins. A successful exploit could allow the attacker to exhaust system resources and cause the device to reload, resulting in a DoS condition. To exploit this vulnerability, the attacker needs valid user credentials on the system.

A vulnerability in the CLI of Cisco FXOS Software could allow an authenticated, local attacker to execute arbitrary commands on the underlying Linux operating system with a privilege level of root on an affected device. The vulnerability is due to insufficient validation of arguments passed to a specific CLI command on the affected device. An attacker could exploit this vulnerability by including malicious input as the argument of an affected command. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux operating system with root privileges. An attacker would need valid administrator credentials to exploit this vulnerability.

A vulnerability in the write-erase feature of Cisco FXOS Software and Cisco NX-OS Software could allow an authenticated, local attacker to configure an unauthorized administrator account for an affected device. The vulnerability exists because the affected software does not properly delete sensitive files when certain CLI commands are used to clear the device configuration and reload a device. An attacker could exploit this vulnerability by logging into an affected device as an administrative user and configuring an unauthorized account for the device. The account would not require a password for authentication and would be accessible only via a Secure Shell (SSH) connection to the device. A successful exploit could allow the attacker to configure an unauthorized account that has administrative privileges, does not require a password for authentication, and does not appear in the running configuration or the audit logs for the affected device. This vulnerability affects Firepower 4100 Series Next-Generation Firewalls, Firepower 9300 Security Appliance, Nexus 1000V Series Switches, Nexus 1100 Series Cloud Services Platforms, Nexus 2000 Series Fabric Extenders, Nexus 3500 Platform Switches, Nexus 4000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCvd13993, CSCvd34845, CSCvd34857, CSCvd34862, CSCvd34879, CSCve35753.

A vulnerability in the Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated attacker to cause process crashes, which could result in a denial of service (DoS) condition on an affected device. The attack vector is configuration dependent and could be remote or adjacent. For more information about the attack vector, see the Details section of this advisory. The vulnerability is due to insufficient error handling when the affected software parses Cisco Fabric Services messages. An attacker could exploit this vulnerability by sending malicious Cisco Fabric Services messages to an affected device. A successful exploit could allow the attacker to cause a reload of an affected device, which could result in a DoS condition.