A vulnerability in the VPN System Logging functionality for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a memory leak that can deplete system memory over time, which can cause unexpected system behaviors or device crashes. The vulnerability is due to the system memory not being properly freed for a VPN System Logging event generated when a VPN session is created or deleted. An attacker could exploit this vulnerability by repeatedly creating or deleting a VPN tunnel connection, which could leak a small amount of system memory for each logging event. A successful exploit could allow the attacker to cause system memory depletion, which can lead to a systemwide denial of service (DoS) condition. The attacker does not have any control of whether VPN System Logging is configured or not on the device, but it is enabled by default.

A vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory handling error when GRE over IPv6 traffic is processed. An attacker could exploit this vulnerability by sending crafted GRE over IPv6 packets with either IPv4 or IPv6 payload through an affected device. A successful exploit could allow the attacker to cause the device to crash, resulting in a DoS condition.