# CVE-2026-20173 — Cisco NX-OS Software

> As of 2026-10-07, CVE-2026-20173 is a MEDIUM-severity vulnerability in Cisco NX-OS Software, CVSS v3.1 5.8, EPSS 0.3% (29.2th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-20173, most recently “Cisco October 2026 Security Advisories: Critical Flaws in Meraki, License (SSM) On-Prem, NX-OS, APIC and Finesse (CVE-2026-76464, CVE-2026-20328, CVE-2026-76485 and others)”.

**Last updated:** 2026-10-07

## What is CVE-2026-20173?

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.

The record classifies CVE-2026-20173 under weakness class [CWE-770](https://intel.threadlinqs.com/cwe/CWE-770). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 3 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 5.8 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 29.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-10-07

## Is CVE-2026-20173 being exploited?

It currently carries a trending score of 42 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Cisco](https://intel.threadlinqs.com/vendors/cisco): NX-OS Software

## How to fix CVE-2026-20173

No vendor patch reference has been recorded for CVE-2026-20173 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-20173

1 tracked threat in the Threadlinqs corpus references CVE-2026-20173, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Cisco October 2026 Security Advisories: Critical Flaws in Meraki, License (SSM) On-Prem, NX-OS, APIC and Finesse (CVE-2026-76464, CVE-2026-20328, CVE-2026-76485 and others)](https://intel.threadlinqs.com/threat/TL-2026-3108) — CRITICAL · 2026-10-09

## Sources

Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10.

**Other references**

- [sec.cloudapps.cisco.com](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-nscpdos-SnderkC7)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-20173
Full detection coverage and IOCs for threats exploiting CVE-2026-20173 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp