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
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
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.
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:
There are no workarounds that address this vulnerability.
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.
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:
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:
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.
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 by X.B. of the Cisco Advanced Security Initiatives Group (ASIG).
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 | 2022-APR-13 |
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