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Security advisories | Jun 19, 2019

SSH Key Vulnerability in Cisco Switches

A vulnerability in the Cisco Nexus 9000 Series Application Centric Infrastructure (ACI) Mode Switch Software has been identified by the security researcher Oliver Matula [1]. If exploited, the vulnerability would allow a remote and unauthenticated threat actor to connect to vulnerable system with root user privileges. At this time, proof of concept code is not publicly available, and exploitation has not been identified in the wild.

A security patch for the vulnerability has been released. It is highly recommended to apply the patch, after a business impact review is performed.

What are we doing about it

  • A MVS (formerly esRECON) plugin is in development and will be added as soon as available to assist in identifying Cisco NX-OS versions affected by this vulnerability

What you should do about it

  • After performing a business impact review, update to version 14.1(1i)

Additional information

This Cisco vulnerability is being tracked as CVE-2019-1804 [2]. All versions of Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode prior to 14.1(1i) are affected.

The source of the vulnerability resides in the use of default SSH key pair that is present in the affected devices. The SSH key pair can be used to access affected devices through an SSH connection using IPv6. IPv4 connections are not vulnerable to this attack.