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Cisco Bug: CSCup97337 - Port CSCub70579 to Nexus 4K

Last Modified

Jan 20, 2017

Products (3)

  • Cisco Nexus 4000 Series Switches
  • Cisco NX-OS Software
  • Cisco Nexus 4001I Switch Module for IBM BladeCenter

Known Affected Releases


Description (partial)


A vulnerability in the TCP stack of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

The vulnerability is due to improper processing of certain TCP packets in the closing sequence of a TCP session while the affected device is in a TIME_WAIT state. 
An attacker could exploit this vulnerability by sending a specific TCP packet to an affected device on a TCP session that is already in a TIME_WAIT state. An exploit 
could allow the attacker to cause a reload of the TCP stack on the affected device, resulting in a DoS condition.

This vulnerability can be exploited using either IPv4 or IPv6 packets. The vulnerability can be triggered by a crafted sequence of TCP packets destined for TCP ports 
listening on the device. The packets may use the IPv4 or IPv6 unicast address of any interface configured on the device.

This vulnerability can be triggered only by traffic destined to an affected device and cannot be exploited using traffic that transits an affected device.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:


Device configured with any service that may use TCP socket, eg: BGP, telnet, http, ssh, etc...
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