Summary

• A vulnerability in the IPv6 implementation of Cisco StarOS could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

  The vulnerability is due to insufficient validation of incoming IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet to an affected device. A successful exploit could allow the attacker to cause an unexpected reload of the device, leading to a DoS condition.

  This vulnerability is specific to IPv6 traffic. IPv4 traffic is not affected.

  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-asr-dos-zJLJFgBf

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco StarOS and have the Vector Packet Processing (VPP) feature enabled. The VPP feature is disabled by default:

  • Cisco ASR 5000 Series Aggregation Services Routers
  • Cisco Virtualized Packet Core-Single Instance (VPC-SI)

  To see if the VPP feature is enabled, an administrator can use the show task table process vpp_main all command. If the command lists the vpp_main process, the feature is enabled. The following is a sample output with the VPP feature enabled:

  [local]swch# show task table process vpp_main all 
          task                                             parent
   cpu facility                 inst    pid pri node  facility      inst    pid
  ----   ----------------------------------------------  -------------------------
   1/0 vpp_main   1005729   5729   0  all  -                0      0

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  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

  Cisco StarOS Major Release	First Fixed Release for This Vulnerability
  Earlier than 21.15	Migrate to 21.15.31.
  21.15	21.15.31
  21.16	21.16.4
  21.16.c	21.16.c11
  21.16.d	Migrate to 21.16.4.
  21.17	21.17.4
  21.18	Not vulnerable.
  21.19	Not vulnerable.

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-asr-dos-zJLJFgBf

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2020-AUG-05

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