A vulnerability in the Cisco Fabric Services component of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a buffer overflow, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient validation of Cisco Fabric Services packets. An attacker could exploit this vulnerability by sending a crafted Cisco Fabric Services packet to an affected device. A successful exploit could allow the attacker to cause a buffer overflow, resulting in process crashes and a DoS condition on the 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: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190306-nxos-fabric-dos This advisory is part of the March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication, which includes 25 Cisco Security Advisories that describe 26 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.
A vulnerability in the Cisco Fabric Services component of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a buffer overflow, resulting in a denial of service (DoS) condition.
The vulnerability is due to insufficient validation of Cisco Fabric Services packets. An attacker could exploit this vulnerability by sending a crafted Cisco Fabric Services packet to an affected device. A successful exploit could allow the attacker to cause a buffer overflow, resulting in process crashes and a DoS condition on the 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:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190306-nxos-fabric-dos
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco NX-OS Software:
For information about determining whether a device is configured to use Cisco Fabric Services, see the Details section of this advisory.
For information about which Cisco NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.
Administrators can check the release of Cisco NX-OS Software that is running on a device by using the show version command in the device CLI. The following example shows the output of this command on a device that is running Cisco NX-OS Software Release 7.0(3)I5(1):
nxos-switch# show version Cisco Nexus Operating System (NX-OS) Software TAC support: http://www.cisco.com/tac Copyright (C) 2002-2016, Cisco and/or its affiliates. All rights reserved. The copyrights to certain works contained in this software are owned by other third parties and used and distributed under their own licenses, such as open source. This software is provided "as is," and unless otherwise stated, there is no warranty, express or implied, including but not limited to warranties of merchantability and fitness for a particular purpose. Certain components of this software are licensed under the GNU General Public License (GPL) version 2.0 or GNU General Public License (GPL) version 3.0 or the GNU Lesser General Public License (LGPL) Version 2.1 or Lesser General Public License (LGPL) Version 2.0. A copy of each such license is available at http://www.opensource.org/licenses/gpl-2.0.php and http://opensource.org/licenses/gpl-3.0.html and http://www.opensource.org/licenses/lgpl-2.1.php and http://www.gnu.org/licenses/old-licenses/library.txt. Software BIOS: version 07.57 NXOS: version 7.0(3)I5(1) [build 7.0(3)I5(0.9)] BIOS compile time: 06/29/2016 NXOS image file is: bootflash:///nxos.7.0.3.I5.0.9.bin NXOS compile time: 8/1/2016 23:00:00 [08/02/2016 00:30:32] . . .
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following Cisco products:
To distribute and synchronize data, Cisco Fabric Services can be configured to use any of the following distribution types:
The vulnerability described in this advisory is due to insufficient input validation that could occur when the affected software processes Cisco Fabric Services packets that it receives during distribution and synchronization operations. Exploitation of the vulnerability does not require any applications to be enabled to use Cisco Fabric Services. Instead, exploitation depends on which Cisco Fabric Services distribution types are configured for a device. In addition, the attack vectors vary based on which distribution types are configured, as follows:
If a device is enabled to use more than one distribution type, the applicable attack vectors for all those distribution types exist for the device.
Administrators can display configuration information and check the distribution status of Cisco Fabric Services for a device by using the show cfs status command in the device CLI, as shown in the following example:
Vulmon
switch# show cfs status
Distribution : Enabled
Distribution over IP : Disabled
IPv4 multicast address : 239.255.70.83
IPv6 multicast address : ff15::efff:4653
Distribution over Ethernet : Disabled
In the preceding example, the Enabled value in the Distribution field of the command output indicates that Cisco Fabric Services is enabled for the device and the device is configured to use the default Cisco Fabric Services distribution type, which is CFSoFC. The Disabled value in the Distribution over IP field and the Distribution over Ethernet field indicates that the device is not additionally configured to use the CFSoIP and CFSoE distribution types.
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 and Alerts 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 release as indicated in the applicable table in this section. To help ensure a complete upgrade solution, customers should consider that this advisory is part of a bundled publication. The following page provides a complete list of bundle advisories: Cisco Event Response: March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.
In the following tables, the left column lists releases of Cisco FXOS Software or Cisco NX-OS Software. The center column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability. The right column indicates whether a release is affected by all the vulnerabilities described in this bundle and which release includes fixes for those vulnerabilities.
Although the releases listed in the right column of each table include fixes for the vulnerabilities, the fix related to the Cisco NX-OS Software Image Signature Verification Vulnerability requires a BIOS upgrade as part of the software upgrade. Customers who are upgrading the software for any of the following products are advised to refer to this advisory for further details about the BIOS upgrade and affected product IDs and BIOS versions:
MDS 9000 Series Multilayer Switches: CSCvj10178
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| 5.2 | 6.2(25) | 6.2(27) |
| 6.2 | 6.2(25) | 6.2(27) |
| 7.3 | 8.1(1b) | 8.3(2) |
| 8.1 | 8.1(1b) | 8.3(2) |
| 8.2 | 8.3(1) | 8.3(2) |
| 8.3 | Not vulnerable | 8.3(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Prior to 7.0(3)I4 | 7.0(3)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I4 | 7.0(3)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I5 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I6 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I7 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 9.2 | Not vulnerable | 9.2(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Prior to 6.0(2)A8 | 6.0(2)A8(10) | 6.0(2)A8(11) |
| 6.0(2)A8 | 6.0(2)A8(10) | 6.0(2)A8(11) |
| 7.0(3) | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 9.2 | Not vulnerable | 9.2(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| 7.0(3)F3 | 7.0(3)F3(3c)1 | 7.0(3)F3(5) |
| 9.2 | Not vulnerable | 9.2(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Prior to 6.2 | Not vulnerable | 6.2(22) |
| 6.2 | 6.2(22) | 6.2(22) |
| 7.2 | 8.2(3) | 8.2(3) |
| 7.3 | Umbrella SMU for CSCvj10178 and CSCvj638071 | 8.2(3) |
| 8.0 | 8.2(3) | 8.2(3) |
| 8.1 | 8.2(3) | 8.2(3) |
| 8.2 | 8.2(3) | 8.2(3) |
| 8.3 | Not vulnerable | 8.3(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Prior to 7.0(3)I4 | 7.0(3)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I4 | 7.0(3)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I5 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I6 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I7 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 9.2 | Not vulnerable | 9.2(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| 7.0(3)F1 | 7.0(3)F3(3c)1 | 7.0(3)F3(5) |
| 7.0(3)F2 | 7.0(3)F3(3c)1 | 7.0(3)F3(5) |
| 7.0(3)F3 | 7.0(3)F3(3c)1 | 7.0(3)F3(5) |
| 9.2 | Not vulnerable | 9.2(2) |
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Prior to 3.1 | 3.2(3j) | 3.2(3j) |
| 3.1 | 3.2(3j) | 3.2(3j) |
| 3.2 | 3.2(3j) | 3.2(3j) |
| 4.0 | 4.0(2a) | 4.0(2a) |
For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, administrators can refer to the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.
For help determining the best Cisco NX-OS Software release for Cisco UCS, refer to the Recommended Releases documents in the release notes for the device.Cisco MDS Series Switches
Cisco Nexus 1000V for VMware Switch
Cisco Nexus 3000 Series and 3500 Series Switches
Cisco Nexus 5000 Series Switches
Cisco Nexus 5500 Platform Switches
Cisco Nexus 6000 Series Switches
Cisco Nexus 7000 Series Switches
Cisco Nexus 9000 Series Switches
Cisco Nexus 9000 Series ACI-Mode Switches
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.
This vulnerability was found during internal security testing.
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.1 | Added SMU fix for Nexus 7000 and 7700 for the 7.3 software release. | Fixed Software | Final | 2019-March-19 |
| 1.0 | Initial public release. | - | Final | 2019-March-06 |
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