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AUSCERT External Security Bulletin Redistribution
Cisco IOx for IOS XE Software Command Injection Vulnerability
25 March 2021
AusCERT Security Bulletin Summary
Product: Cisco IOx for IOS XE Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Root Compromise -- Existing Account
Execute Arbitrary Code/Commands -- Existing Account
CVE Names: CVE-2021-1384
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Cisco IOx for IOS XE Software Command Injection Vulnerability
Advisory ID: cisco-sa-iox-cmdinj-RkSURGHG
First Published: 2021 March 24 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvw64798
CVE Names: CVE-2021-1384
o A vulnerability in Cisco IOx application hosting environment of Cisco IOS
XE Software could allow an authenticated, remote attacker to inject
commands into the underlying operating system as the root user.
This vulnerability is due to incomplete validation of fields in the
application packages loaded onto IOx. An attacker could exploit this
vulnerability by creating a crafted application . tar file and loading it
onto the device. A successful exploit could allow the attacker to perform
command injection into the underlying operating system as the root user.
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
At the time of publication, this vulnerability affected Cisco IOS XE
Software releases 16.3.1 and later if they were configured with the Cisco
IOx application hosting infrastructure.
The Cisco IOx application hosting infrastructure is not enabled by default.
See the Details section in the bug ID(s) at the top of this advisory for
the most complete and current information.
Assess the Cisco IOx Application Hosting Environment
There are two methods for assessing the IOx application hosting
Option 1: Use the show iox-service Command
To determine the status of IOx functionality, use the show iox-service
command in privileged EXEC mode, as shown in the following example:
IOx Infrastructure Summary:
IOx service (CAF) : Running
IOx service (HA) : Running
IOx service (IOxman) : Running
Libvirtd : Running
The device is vulnerable if IOx service (CAF) is in the Running state. If
any statement in the following list is true, the device is not affected by
the vulnerability described in this advisory:
IOx service (CAF) is in the Not Running state
The show iox-service privileged EXEC mode command returns no output
The show iox-service privileged EXEC mode command returns an error
Option 2: Use the iox Configuration Command
As an alternative, check the running configuration for the iox
configuration command, as shown in the following example:
Router#sh run | include iox
The device is vulnerable if the output contains a line with only iox , as
shown in the preceding example. If the iox configuration command does not
return output or this command returns an error, the device is not affected
by the vulnerability described in 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
Other platforms that support Cisco IOx
IOS XR Software
o There are no workarounds that address this vulnerability.
Cisco recommends that customers who do not want to use the Cisco IOx
application hosting environment mitigate this vulnerability by disabling
IOx permanently on the device by using the no iox configuration command.
While this mitigation has been deployed and was 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
o 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
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.
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 Cisco would like to thank Orange Group for reporting this vulnerability.
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-MAR-24 |
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