A vulnerability in TCP connection handling by Cisco Virtual Topology System (VTS) devices could allow an unauthenticated, remote attacker to disable TCP ports and cause a denial of service (DoS) condition due to high CPU and memory utilization.

The vulnerability is due to a lack of rate limiting in the TCP listen application. An attacker could exploit this vulnerability by sending a crafted TCP traffic stream in which specific types of TCP packets are flooded to an affected device. An example could be a TCP packet stream in which the TCP FIN bit is set in all the TCP packets. An exploit could allow the attacker to cause certain TCP listen ports to stop accepting incoming connections for a period of time or until the device is restarted. In addition, during the DoS attack, system resources such as CPU and memory can be exhausted.

Cisco has not released software updates that address this vulnerability. There are no workarounds that mitigate this vulnerability.

This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151123-vts

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