Vulnerabilities & Exploits

Cisco NX-API overflow threatens Nexus management planes

Cisco disclosed CVE-2026-76471, a critical heap overflow in NX-OS NX-API that can affect Nexus 3000 and 9000 switches with NX-API enabled, plus UCS 6300 fabric interconnects. On UCS 6300, Cisco says exploitation also needs valid low-privilege credentials, so the exposed set is narrower than the headline suggests.

The bug is in how the management API handles a crafted HTTP request: instead of rejecting it, the device can overrun memory and let an attacker run code as root or crash the process. Cisco also warns the same flaw can trigger device reboots and denial of service, which matters because the vulnerable path sits on the management plane, not the forwarding plane.

That leaves the risk concentrated on infrastructure gear where NX-API was turned on in the first place. For teams that expose device APIs, the question is less whether every Nexus box is affected than which management interfaces are live and which ones inherit the fix lag.

1 source · 10h ago

Timeline

• Oct 13 Reported by INCIBE-CERT

Sources

• Oct 13 INCIBE-CERT

  Desbordamiento de búfer basado en montículo en NX-OS Software de Cisco

  Cisco ha publicado una vulnerabilidad de severidad crítica que, en caso de ser explotada, podría permi

  original

Vendor digest: Cisco

Part of the PlainSec briefing for 2026-10-13

Every edition of this story: Cisco NX-API overflow threatens Nexus management planes

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