A vulnerability in the restricted shell of Cisco Expressway Series could allow an authenticated, local attacker to perform command injection attacks on the underlying operating system and elevate privileges to root. To exploit this vulnerability, the attacker must have Administrator-level credentials with read-write privileges on an affected device. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by submitting a series of crafted CLI commands. A successful exploit could allow the attacker to escape the restricted shell and gain root privileges on the underlying operating system of the affected device. Note: Cisco Expressway Series refers to Cisco Expressway Control (Expressway-C) devices and Cisco Expressway Edge (Expressway-E) devices.

A vulnerability in the administrative web interface of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an authenticated, remote attacker to execute code with user-level privileges on the underlying operating system. The vulnerability is due to insufficient validation of the content of upgrade packages. An attacker could exploit this vulnerability by uploading a malicious archive to the Upgrade page of the administrative web interface. A successful exploit could allow the attacker to execute code with user-level privileges on the underlying operating system.

A vulnerability in the XCP Router service of the Cisco Unified Communications Manager IM & Presence Service (CUCM IM&P) and the Cisco TelePresence Video Communication Server (VCS) and Expressway could allow an unauthenticated, remote attacker to cause a temporary service outage for all IM&P users, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by sending a malicious IPv4 or IPv6 packet to an affected device on TCP port 7400. An exploit could allow the attacker to overread a buffer, resulting in a crash and restart of the XCP Router service. Cisco Bug IDs: CSCvg97663, CSCvi55947.

Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service.