CVE-2026-76456 Cisco CVE debrief

Who should care

Defenders responsible for Cisco NX-OS Software, Cisco NX-OS System Software in ACI Mode, and Cisco Unified Computing System (Managed) deployments should assess exposure and prioritize verification and potential updates.

Why it matters

CVE-2026-76456 is a HIGH severity vulnerability related to improper input validation in Cisco NX-OS Software, Cisco NX-OS System Software in ACI Mode, and Cisco Unified Computing System (Managed). Defenders should prioritize verifying exposure and assessing the need for updates or patches.

• Verify exposure in Cisco NX-OS Software, Cisco NX-OS System Software in ACI Mode, and Cisco Unified Computing System (Managed) deployments
• Assess the need for updates or patches to address the vulnerability
• Implement Cisco's security advisory recommendations to mitigate the vulnerability

Technical summary

CVE-2026-76456 is related to improper input validation of special elements used in a command in Cisco NX-OS Software, Cisco NX-OS System Software in ACI Mode, and Cisco Unified Computing System (Managed). This vulnerability has a CVSS score of 8.6, indicating high severity. The vulnerability was internally discovered by Cisco and addressed through their software hardening release. Defenders should prioritize verifying exposure in their deployments and assess the need for updates or patches to mitigate the vulnerability.

Defensive priority

Defenders should prioritize verifying exposure in their Cisco NX-OS Software, Cisco NX-OS System Software in ACI Mode, and Cisco Unified Computing System (Managed) deployments, and assess the need for updates or patches.

Recommended defensive actions

• Verify Cisco NX-OS Software, Cisco NX-OS System Software in ACI Mode, and Cisco Unified Computing System (Managed) deployments for exposure
• Assess the need for updates or patches
• Review and implement Cisco's security advisory recommendations
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on the vulnerability and affected products. Cisco has provided a security advisory (cisco-sa-hardening-nxosw1-cWzSbtR) addressing these vulnerabilities. Evidence is limited to CVE Program and Cisco-provided information. Defenders should verify exposure in their specific deployments and assess the need for updates or patches based on this information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.