Cisco Security Advisory
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
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As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco NX-OS Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.
These vulnerabilities were found during internal testing and are not known to be actively exploited. To assist customers in patching and streamline the disclosure process, Cisco has grouped these issues by their underlying vulnerability class — Common Weakness Enumeration (CWE) — and assigned a single Common Vulnerabilities and Exposures identifier (CVE ID).
Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-nxosw1-cWzSbtR
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Vulnerable Products
These vulnerabilities affect the following Cisco products if they are running a vulnerable release of Cisco NX-OS Software, regardless of device configuration:
- MDS 9000 Series Multilayer Switches
- Nexus 3000 Series Switches
- Nexus 7000 Series Switches
- Nexus 9000 Series Fabric Switches in ACI mode
- Nexus 9000 Series Switches in standalone NX-OS mode
- UCS 6300 Series Fabric Interconnects
- UCS 6400 Series Fabric Interconnects
- UCS 6500 Series Fabric Interconnects
- UCS 6600 Series Fabric Interconnects
- UCS X-Series Direct Fabric Interconnect 9108 100G
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.
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The following table outlines the vulnerability classes that are addressed in these software hardening releases. The CVSS score that is assigned to each CVE ID represents the maximum potential severity of the single most impactful underlying vulnerability within that specific CWE category.
CVE ID Highest CVSS Score Vulnerability Class (Highest-Level CWE) Description CVE-2026-76453 8.8 CWE-707 Improper neutralization (covers command, OS, and argument injection) CVE-2026-76455 9.8 CWE-284 Improper access control (covers authorization, authentication, privileges, and bypasses) CVE-2026-76456 8.6 CWE-20 Improper input validation (covers input validation, path traversal, and external path control) CVE-2026-76457 8.6 CWE-125 Out-of-bounds read (covers buffer over-read and exposure of sensitive information) CVE-2026-76458 8.6 CWE-703 Improper handling of exceptional conditions (covers uncaught exceptions and reachable assertions) CVE-2026-76459 9.8 CWE-787 Out-of-bounds write (covers stack-based buffer overflow, heap-based buffer overflow, classic buffer overflow, and incorrect buffer size calculation)
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There are no workarounds that address these vulnerabilities.
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To remediate these vulnerabilities and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.
Fixed Releases
In the following tables, the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerabilities that are described in this advisory and the first release that includes the fix for these vulnerabilities. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.
MDS 9000 Series Multilayer Switches
Cisco NX-OS Software Release First Fixed Release 9.3 and earlier Migrate to a fixed release. 9.4 9.4(5a) Nexus 3000 Series Switches and Nexus 9000 Series Switches in Standalone NX-OS mode
Cisco NX-OS Software Release First Fixed Release 10.3 and earlier 10.3(10) 10.4 10.4(8) 10.5 10.5(6) 10.6 10.6(4) Nexus 7000 Series Switches
Cisco NX-OS Software Release First Fixed Release 8.3 and earlier Migrate to a fixed release. 8.4 8.4(14) Nexus 9000 Series Fabric Switches in ACI mode
Cisco NX-OS Software Release First Fixed Release 16.0 and earlier 16.0(9h) 16.1 16.1(6g) 16.2 16.2(3g) UCS 6300, 6400, 6500, and 6600 Series and 9108 100G Fabric Interconnects
Cisco UCS Software Release First Fixed Release for UCS Manager Managed Mode First Fixed Release for UCS Intersight Managed Mode 4.2 and earlier Migrate to a fixed release. Migrate to a fixed release. 4.3 4.3(6j) 4.3(6.260049)
4.3(6.260059)6.0 6.0(2e) 6.0(2.260080) Note: Release 4.3(6.260059) is for Cisco 9108 100G Fabric Interconnects only.
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 vulnerabilities that are described in this advisory.
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These vulnerabilities were found during internal security testing using existing testing processes as well as frontier AI models.
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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.
For additional information on Cisco's vulnerability management, disclosure cadence, and software patching strategy, see Cisco's Transition to a Risk-Based Vulnerability Disclosure Model.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2026-OCT-07
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SOFTWARE DOWNLOADS AND TECHNICAL SUPPORT
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. Please note that customers may download only software that was procured from Cisco directly or through a Cisco authorized reseller or partner and for which the license is still valid.
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 Technical Assistance Center (TAC). 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.
When considering software upgrades, customers are advised to regularly consult the advisories for the relevant Cisco products 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.
LEGAL DISCLAIMER DETAILS
CISCO DOES NOT MAKE ANY EXPRESS OR IMPLIED GUARANTEES OR WARRANTIES OF ANY KIND, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. WITHOUT LIMITING THE GENERALITY OF THE FOREGOING, CISCO DOES NOT GUARANTEE THE ACCURACY OR COMPLETENESS OF THIS INFORMATION. THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
Copies or summaries of the information contained in this Security Advisory may lack important information or contain factual errors. Customers are advised to visit the Cisco Security Advisories page for the most recent version of this Security Advisory. The Cisco Product Security Incident Response Team (PSIRT) assesses only the affected and fixed release information that is documented in this advisory. See the Cisco Security Vulnerability Policy for more information.