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AUSCERT External Security Bulletin Redistribution
ESB-2022.1608
Cisco IOS XE Software Tool Command Language Privilege
Escalation Vulnerability
14 April 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2022-20676
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-priv-esc-grbtubU
Comment: CVSS (Max): 5.1 CVE-2022-20676 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N)
CVSS Source: Cisco Systems
Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N
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Cisco IOS XE Software Tool Command Language Privilege Escalation Vulnerability
Priority: Medium
Advisory ID: cisco-sa-iosxe-priv-esc-grbtubU
First Published: 2022 April 13 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvy35833
CVE Names: CVE-2022-20676
CWEs: CWE-250
Summary
o A vulnerability in the Tool Command Language (Tcl) interpreter of Cisco IOS
XE Software could allow an authenticated, local attacker to escalate from
privilege level 15 to root- level privileges.
This vulnerability is due to insufficient input validation of data that is
passed into the Tcl interpreter. An attacker could exploit this
vulnerability by loading malicious Tcl code on an affected device. A
successful exploit could allow the attacker to execute arbitrary commands
as root . By default, Tcl shell access requires privilege level 15.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is part of the April 2022 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: April 2022
Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
Publication.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-priv-esc-grbtubU
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco devices if
they were running a vulnerable release of Cisco IOS XE Software and
supported the tclsh command.
Note: Devices are not considered vulnerable if they do not support the
command or if the command returns an error.
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 these vulnerabilities.
Cisco has confirmed that these vulnerabilities do not affect the following
Cisco products:
IOS Software
IOS XR Software
Meraki products
NX-OS Software
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
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
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.
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
following ways:
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.
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.
Source
o This vulnerability was found during internal security testing by X.B. of
the Cisco Advanced Security Initiatives Group (ASIG).
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: April 2022 Semiannual Cisco IOS and IOS XE Software
Security Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-priv-esc-grbtubU
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2022-APR-13 |
+----------+---------------------------+----------+--------+--------------+
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