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AUSCERT External Security Bulletin Redistribution
Cisco IOS XE Software Plug-and-Play Privilege Escalation Vulnerability
25 March 2021
AusCERT Security Bulletin Summary
Product: Cisco IOS XE Software Plug-and-Play
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Administrator Compromise -- Existing Account
CVE Names: CVE-2021-1442
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Cisco IOS XE Software Plug-and-Play Privilege Escalation Vulnerability
Advisory ID: cisco-sa-ios-xe-pnp-priv-esc-AmG3kuVL
First Published: 2021 March 24 16:00 GMT
Version 1.0: Final
Cisco Bug IDs: CSCvt41030
CVE Names: CVE-2021-1442
o A vulnerability in a diagnostic command for the Plug-and-Play (PnP)
subsystem of Cisco IOS XE Software could allow an authenticated, local
attacker to elevate privileges to the level of an Administrator user (level
15) on an affected device.
The vulnerability is due to insufficient protection of sensitive
information. An attacker with low privileges could exploit this
vulnerability by issuing the diagnostic CLI show pnp profile when a
specific PnP listener is enabled on the device. A successful exploit could
allow the attacker to obtain a privileged authentication token. This token
can be used to send crafted PnP messages and execute privileged commands on
the targeted system.
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:
This advisory is part of the March 2021 release of the Cisco IOS and IOS XE
Software Security Advisory Bundled Publication. For a complete list of the
advisories and links to them, see Cisco Event Response: March 2021
Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
o Vulnerable Products
This vulnerability affects devices if they are running a vulnerable release
of Cisco IOS XE Software.
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.
Cisco has confirmed that this vulnerability does not affect the following
IOS XR Software
o A workaround exists for devices that have TACACS+ authentication,
authorization, and accounting (AAA) command authorization configured.
Administrators can use this feature to deny access to the non-privileged
users to the show pnp profile command.
For information on how to implement TACACS+ (AAA), see the Authentication
Authorization and Accounting Configuration Guide that can be found in the
Configuration Guides page for Cisco IOS XE Software.
Customers who may not want to apply the preceding workaround can disable
the HTTP Server feature to eliminate the attack vector for this
vulnerability. This may be a suitable mitigation until affected devices can
be upgraded. To disable the HTTP Server feature, use the no ip http server
or no ip http secure-server command in global configuration mode. If both
the HTTP server and HTTPS server are in use, both commands are required to
disable the HTTP Server feature.
While these workarounds and mitigations have been deployed and were proven
successful in a test environment, customers should determine the
applicability and effectiveness in their own environment and under their
own use conditions. Customers should be aware that any workaround or
mitigation that is implemented may negatively impact the functionality or
performance of their network based on intrinsic customer deployment
scenarios and limitations. Customers should not deploy any workarounds or
mitigations before first evaluating the applicability to their own
environment and any impact to such environment.
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 IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker to identify
any Cisco Security Advisories that impact a specific software release and
the earliest release that fixes the vulnerabilities described in each
advisory ("First Fixed"). If applicable, the tool also returns the earliest
release that fixes all the vulnerabilities described in all the advisories
identified ("Combined First Fixed").
Customers can use the Cisco Software Checker to search advisories in the
Choose the software and one or more releases
Upload a .txt file that includes a list of specific releases
Enter the output of the show version command
After initiating a search, customers can customize the search to include
all Cisco Security Advisories, a specific advisory, or all advisories in
the most recent bundled publication.
Customers can also use the following form to determine whether a release is
affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
Software release-for example, 15.1(4)M2 or 3.13.8S :
[ ] [Check]
By default, the Cisco Software Checker includes results only for
vulnerabilities that have a Critical or High Security Impact Rating (SIR).
To include results for Medium SIR vulnerabilities, customers can use the
Cisco Software Checker on Cisco.com and check the Medium check box in the
drop-down list under Impact Rating when customizing a search.
For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
IOS XE Software release.
Exploitation and Public Announcements
o 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.
o This vulnerability was found during internal security testing by X.B., of
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.
Related to This Advisory
o Cisco Event Response: March 2021 Semiannual Cisco IOS and IOS XE Software
Security Advisory Bundled Publication
| Version | Description | Section | Status | Date |
| 1.0 | Initial public release. | - | Final | 2021-MAR-24 |
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