A vulnerability in a proprietary device driver in the kernel of Cisco TelePresence Multipoint Control Unit (MCU) Software could allow an unauthenticated, remote attacker to execute arbitrary code or cause a denial of service (DoS) condition. The vulnerability is due to improper size validation when reassembling fragmented IPv4 or IPv6 packets. An attacker could exploit this vulnerability by sending crafted IPv4 or IPv6 fragments to a port receiving content in Passthrough content mode. An exploit could allow the attacker to overflow a buffer. If successful, the attacker could execute arbitrary code or cause a DoS condition on the affected system. Cisco TelePresence MCU platforms TelePresence MCU 5300 Series, TelePresence MCU MSE 8510 and TelePresence MCU 4500 are affected when running software version 4.3(1.68) or later configured for Passthrough content mode. Cisco has released software updates that address this vulnerability. Workarounds that address this vulnerability are not available, but mitigations are available. Cisco Bug IDs: CSCuu67675.