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AUSCERT External Security Bulletin Redistribution
Cisco Enterprise NFV Infrastructure Software Authentication
2 September 2021
AusCERT Security Bulletin Summary
Product: Enterprise NFV Infrastructure Software (NFVIS)
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Administrator Compromise -- Remote/Unauthenticated
CVE Names: CVE-2021-34746
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Cisco Enterprise NFV Infrastructure Software Authentication Bypass
Advisory ID: cisco-sa-nfvis-g2DMVVh
First Published: 2021 September 1 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvz16015
CVE Names: CVE-2021-34746
o A vulnerability in the TACACS+ authentication, authorization and accounting
(AAA) feature of Cisco Enterprise NFV Infrastructure Software (NFVIS) could
allow an unauthenticated, remote attacker to bypass authentication and log
in to an affected device as an administrator.
This vulnerability is due to incomplete validation of user-supplied input
that is passed to an authentication script. An attacker could exploit this
vulnerability by injecting parameters into an authentication request. A
successful exploit could allow the attacker to bypass authentication and
log in as an administrator to the 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:
o Vulnerable Products
This vulnerability affects Cisco Enterprise NFVIS Release 4.5.1 if the
TACACS external authentication method is configured.
Determine TACACS External Authentication Configuration
To determine if a TACACS external authentication feature is enabled on a
device, use the show running-config tacacs-server command. The following
example shows the output of the show running-config tacacs-server command
on Cisco Enterprise NFVIS when TACACS external authentication is enabled:
nfvis# show running-config tacacs-server
tacacs-server host 192.168.1.1
If the output of the show running-config tacacs-server command is No
entries found , the TACACS external authentication feature is not enabled.
Alternatively, check the configuration through the GUI. Choose
Configuration > Host > Security > User and Roles . If a TACACS+ host is
defined under External Authentication , the device is considered to be
Configurations that are using RADIUS or local authentication only are not
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
o There are no workarounds that address this vulnerability.
o 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
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
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
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
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
Cisco fixed this vulnerability in Cisco Enterprise NFVIS releases 4.6.1 and
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is aware that
proof-of-concept exploit code is available for the vulnerability described
in this advisory.
The Cisco PSIRT is not aware of any malicious use of the vulnerability that
is described in this advisory.
o Cisco would like to thank Cyrille Chatras of Orange Group for reporting
Cisco Security Vulnerability Policy
o 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 |
| 1.0 | Initial public release. | - | Final | 2021-SEP-01 |
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