Medium [CVE-2026-20173] Cisco NX-OS Software Control Plane Denial of Service Vulnerability
This medium-severity Cisco advisory covers CVE-2026-20173 affecting NX-OS Software, Nexus 7000 Series Switches, Nexus 3000 Series Switches.
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Summary
A vulnerability in Cisco NX-OS Software could allow an unauthenticated, remote attacker to exhaust system resources, causing a denial of service (DoS) condition.
This vulnerability exists because rate limiting was improperly applied to some protocols. An attacker could exploit this vulnerability by sending a high rate of UDP or TCP connections to a data plane interface on an affected device.
A successful exploit could allow the attacker to cause instability to various routing and control plane protocols through some packet loss and temporary disruptions, causing a DoS condition. This DoS condition will clear without manual intervention soon after the high rate of traffic is stopped.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of October 7, 2026, Security Advisories.
For further documentation of improvements and fixes in Cisco NX-OS Software, see Cisco NX-OS Software Security Hardening Release: October 2026.
Affected products named by the advisory: Nexus 7000 Series Switches; Nexus 3000 Series Switches; Nexus 9000 Series Switches.
- Scope: At the time of publication, this vulnerability affected the following Cisco products if they were running a vulnerable release of Cisco NX-OS Software, regardless of device configuration:
Official advisory · high-confidence parse· fetched 10 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 10 hours ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
Official advisory · high-confidence parse· fetched 10 hours ago·verify at source
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