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From NX-API to Root: Reading the Cisco Advisory for CVE-2026-76471

#cisco #advisoryanalysis #nxapi

From NX-API to Root: Reading the Cisco Advisory for CVE-2026-76471

Vulnerability overview

CVE-2026-76471 occupies the top of Cisco's October 2026 NX-OS batch with a CVSSv3 score of 9.8, alongside six hardening identifiers that Cisco grouped by weakness class. The vendor reports no exploitation for any of the seven. What follows is a close reading of what the advisory does and does not say.

Mechanism and exploitation conditions

Cisco attributes the defect to insufficient input validation of data sent to NX-API. An attacker submits a crafted HTTP request, and a successful attempt yields root-level code execution or a device reload. The advisory is precise about exposure: NX-API is disabled by default on Nexus 3000 and Nexus 9000 switches, so the switch API is not reachable on a stock build. UCS 6300 fabric interconnects reach the same code path through the UCS Manager XML API, which is enabled by default; because that route requires low-privileged credentials, Cisco assigns it a High rating rather than Critical.

Impact

Root on a NX-OS platform means control of a device that carries production traffic for many systems. The reload outcome is disruptive; the code execution outcome is worse because it grants lasting access. The hardening release bundled with this disclosure applies regardless of configuration and therefore reaches devices that the NX-API defect alone would not.

Affected products and scope

Nexus 3000, Nexus 9000 in standalone mode and UCS 6300 fabric interconnects carry the NX-API defect. MDS 9000, Nexus 7000, Nexus 9000 in ACI mode and UCS 6400 through 6600 are covered by the hardening release.

Exposure context

A ZoomEye fingerprint search for app="Cisco NX-OS" returned 586 assets during this analysis, and vul.cve="CVE-2026-76471" returned nothing indexed. Newly issued identifiers commonly take time to appear in vulnerability-aware indexes, so the absence of results is not evidence that nothing is exposed.

Remediation and mitigations

Cisco lists no workaround. First fixed releases are 10.3(10), 10.4(8), 10.5(6) and 10.6(4) for Nexus 3000 and Nexus 9000 standalone; 16.0(9h), 16.1(6g) and 16.2(3g) for ACI mode; 9.4(5a) for MDS 9000; 8.4(14) for Nexus 7000; and 4.3(6j) or 6.0(2e) in UCS Manager mode for fabric interconnects, with matching Intersight builds. Operators can check exposure with show feature | include nxapi, and a temporary Live Protect shield is available while upgrades are scheduled.

References

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