Cisco Security Advisory
Cisco IOS XR Software Image Verification Vulnerability
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CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N/E:X/RL:X/RC:X
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A vulnerability in Cisco IOS XR Software image verification checks could allow an authenticated, local attacker to execute arbitrary code on the underlying operating system.
This vulnerability is due to a time-of-check, time-of-use (TOCTOU) race condition when an install query regarding an ISO image is performed during an install operation that uses an ISO image. An attacker could exploit this vulnerability by modifying an ISO image and then carrying out install requests in parallel. A successful exploit could allow the attacker to execute arbitrary code on an 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-lnt-L9zOkBz5This advisory is part of the September 2023 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
At the time of publication, these vulnerabilities affected the following Cisco devices if they were running a vulnerable release of Cisco IOS XR Software:
- 8000 Series Routers
- Network Convergence System (NCS) 540 Series Routers that are running the NCS540L images
- Network Convergence System (NCS) 5700 Series Routers that are running the NCS5700 images (NCS-57B1-5DSE-SYS, NCS-57B1-6D24-SYS and NCS-57C1-48Q6-SYS)
For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
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 these vulnerabilities do 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.
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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.
Fixed Releases
At the time of publication, the release information in the following table(s) was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerability described in this advisory and which release included the fix for this vulnerability.
Cisco IOS XR Release First Fixed Release Earlier than 7.5.2 Not affected. 7.5.2 and later Migrate to a fixed release. 7.6 and later Not affected. 7.7 and later 7.10.1 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 2023-SEP-13
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