Summary

• A vulnerability in a CLI command of Cisco IOS XR Software for the Cisco 8000 Series Routers and Network Convergence System 540 Series Routers running NCS540L software images could allow an authenticated, local attacker to elevate their privilege to root. To exploit this vulnerability, an attacker would need to have a valid account on an affected device.

  The vulnerability is due to insufficient validation of command line arguments. An attacker could exploit this vulnerability by authenticating to the device and entering a crafted command at the prompt. A successful exploit could allow an attacker with low-level privileges to escalate their privilege level to root.

  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:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-pe-QpzCAePe

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco IOS XR Software on the following platforms:

  • Cisco 8000 Series Routers if running releases earlier than the first fixed release.
  • Network Convergence System 540 Series Routers 7.x releases if running releases earlier than the first fixed software release and running the NCS540L images.

  Determine the Software Version

  To determine if the device is running an NCS540L image, administrators can log into the device and issue the show version command. If the output indicates LNT then it is running on an affected device.

  Router#show version
  Cisco IOS XR Software, Version 7.0.1 LNT
  Copyright (c) 2013-2019 by Cisco Systems, Inc.
  Build Information:
   Built By     : xyz
   Built On     : Sat Jun 29 22:45:27 2019
   Build Host   : iox-lnx-064
   Workspace    : ../7.0.1/NCS540L/ws/
   Version      : 7.0.1
   Label        : 7.0.1
  cisco NCS540L
  System uptime is 41 minutes
  

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:
  https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

  Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.

  When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, to determine exposure and a complete upgrade solution.

  In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

  Customers Without Service Contracts

  Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html

  Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.

  Fixed Releases

  Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table(s):

  Platform	Cisco IOS XR Software Release
  Cisco 8000 Series Routers	7.0.12 7.2.1
  Network Convergence System 540 Series Routers	7.2.1

  Cisco has released software maintenance upgrades (SMUs) to address this vulnerability. Customers who require SMUs for other platforms and releases are advised to contact their support organization.

  Cisco IOS XR Software Release	Platform	SMU Name
  7.1.2	NCS540L	ncs540l-7.1.2.CSCvs35027

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

• This vulnerability was found during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-pe-QpzCAePe

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2021-FEB-03

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