Cisco NX-OS Software: Out-of-bounds read vulnerability

Summary

Cisco NX-OS Software on Nexus, MDS 9000 and UCS Fabric Interconnect devices contains an out-of-bounds read vulnerability (CWE-125). The vulnerability can be triggered remotely over the network without authentication or user interaction, with a high impact on availability. Cisco's advisory states that the vulnerabilities were found internally and that no exploitation is known.

Affected

• MDS 9000 Series: 9.3 and earlier
• Nexus 3000 and Nexus 9000 in standalone NX-OS mode: 10.3 and earlier, 10.4 before 10.4(8), 10.5 before 10.5(6), 10.6 before 10.6(4)
• Nexus 7000 Series: 8.3 and earlier
• Nexus 9000 in ACI mode: 16.0 and earlier, 16.1 before 16.1(6g), 16.2 before 16.2(3g)
• UCS Fabric Interconnects 6300, 6400, 6500, 6600 and UCS X-Series 9108 100G: 4.2 and earlier
• The CVE record also lists further ACI and UCS release strings. These were not verified against Cisco, and Cisco's fixed-release table is authoritative.

Fixed in

• MDS 9000: 9.4(5a) or later
• Nexus 3000 and standalone Nexus 9000: 10.3(10), 10.4(8), 10.5(6) or 10.6(4) or later
• Nexus 7000: 8.4(14) or later
• Nexus 9000 in ACI mode: 16.0(9h), 16.1(6g) or 16.2(3g) or later
• UCS Fabric Interconnects in UCS Manager mode: 4.3(6j) or 6.0(2e) or later; for the Cisco 9108 100G: 4.3(6.260059) or later
• UCS Fabric Interconnects in Intersight managed mode: 4.3(6.260049) or 6.0(2.260080) or later
• Check the exact release for your platform with the Cisco Software Checker.

Workaround

• Cisco states that no workarounds are available.
• Upgrading to a fixed release is the only remediation.

Exploitation

• Cisco PSIRT is not aware of any public announcements or malicious use.
• CISA SSVC assessment: exploitation none, automatable yes, technical impact partial.
• No public proof of concept found. Third-party sources report that the item is not listed in the CISA KEV catalog; verify this directly in the catalog.

Our recommendation

• Identify all Nexus, MDS 9000 and UCS Fabric Interconnect devices and their running NX-OS or UCS versions.
• Plan a maintenance window and upgrade affected devices to the fixed releases listed above.
• Restrict access to management and control-plane interfaces to trusted networks and do not expose them to the internet. This is an interim measure, not a vendor-documented mitigation.
• Monitor the Cisco advisory for updates, including to the NVD record and the confidentiality impact.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Cisco Security Advisory: NX-OS Software Security Hardening Release October 2026 sec.cloudapps.cisco.com
• Cisco Security Advisory (cisco.com mirror) www.cisco.com
• OpenCVE: CVE-2026-76457 app.opencve.io
• Vulners: CVE-2026-76457 (Rapid7 listing) vulners.com
• VulDB: CVE-2026-76457 vuldb.com

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 09:12.