Cisco Security Advisory
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CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
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A vulnerability in the SSH client feature of Cisco IOS XR Software for Cisco 8000 Series Routers and Cisco Network Convergence System (NCS) 540 Series and 5700 Series Routers could allow an authenticated, local attacker to elevate privileges on an affected device.
This vulnerability is due to insufficient validation of arguments that are included with the SSH client CLI command. An attacker with low-privileged access to an affected device could exploit this vulnerability by issuing a crafted SSH client command to the CLI. A successful exploit could allow the attacker to elevate privileges to root on 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:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-ssh-privesc-eWDMKew3This advisory is part of the March 2024 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2023 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication.
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Vulnerable Products
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco IOS XR Software:
- 8000 Series Routers
- IOS XRd Control Plane
- IOS XRd vRouter
- NCS 540 Series Routers that are running the NCS540L images
- NCS 5700 Series Routers (NCS-57B1-5DSE-SYS, NCS-57B1-6D24-SYS, and NCS-57C1-48Q6-SYS)
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine the Software Release
To determine whether the device is running an affected software image, use the show version command in the device CLI. If the output indicates LNT, as shown in the following example, then the device is affected by this vulnerability:
Router# show version
Cisco IOS XR Software, Version 7.5.2 LNT
Copyright (c) 2013-2022 by Cisco Systems, Inc.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 Cisco products:
- IOS Software
- IOS XE Software
- NX-OS Software
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There are no workarounds that address this vulnerability.
However, as a mitigation, customers who have configured authentication, authorization, and accounting (AAA) services to provide command authorization may restrict access to the ssh command in the authorization policy that is defined on their AAA server.
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 environment.
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Cisco has released free software updates that address the vulnerability described in this advisory. Customers with service contracts that entitle them to regular software updates should obtain security fixes through their usual update channels.
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 software license:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.htmlAdditionally, 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.
The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool.
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.
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/en/us/support/web/tsd-cisco-worldwide-contacts.html
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 upgrade.
Fixed Releases
In the following table, the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerability that is described in this advisory and the first release that includes the fix for this vulnerability. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.
Cisco IOS XR Software Release First Fixed Release 7.3.2 Migrate to a fixed release. 7.4 Migrate to a fixed release. 7.5 Migrate to a fixed release. 7.6 Migrate to a fixed release. 7.7 Migrate to a fixed release. 7.8 Migrate to a fixed release. 7.9 Migrate to a fixed release. 7.10 7.10.2 The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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This vulnerability was found during internal security testing.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2024-MAR-13
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