---
id: CVE-2026-20038
title: "A vulnerability in the endpoint group (EPG) contract functionality of Cisco Nexus 9000 Series Fabric Switches in ACI Mode could allow an unauthenticated, remote attacker to bypass configured EPG contracts.\r\n\r\nThis vulnerability is due to…"
summary: "A vulnerability in the endpoint group (EPG) contract functionality of Cisco Nexus 9000 Series Fabric Switches in ACI Mode could allow an unauthenticated, remote attacker to bypass configured EPG contracts.\r\n\r\nThis vulnerability is due to…"
severity: medium
cvss: 5.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N'
cwe:
  - CWE-284
vendor: Cisco
product: Cisco NX-OS System Software in ACI Mode
affected:
  - nx-os_system_software_in_aci_mode 15.2(1g)
  - nx-os_system_software_in_aci_mode 15.2(2e)
  - nx-os_system_software_in_aci_mode 15.2(2f)
  - nx-os_system_software_in_aci_mode 15.2(2g)
  - nx-os_system_software_in_aci_mode 15.2(2h)
  - nx-os_system_software_in_aci_mode 15.2(3f)
  - nx-os_system_software_in_aci_mode 15.2(3e)
  - nx-os_system_software_in_aci_mode 15.2(3g)
  - nx-os_system_software_in_aci_mode 15.2(4d)
  - nx-os_system_software_in_aci_mode 15.2(4e)
  - nx-os_system_software_in_aci_mode 15.2(5c)
  - nx-os_system_software_in_aci_mode 15.2(5d)
  - nx-os_system_software_in_aci_mode 16.0(1g)
  - nx-os_system_software_in_aci_mode 15.2(5e)
  - nx-os_system_software_in_aci_mode 15.2(4f)
  - nx-os_system_software_in_aci_mode 15.2(6e)
  - nx-os_system_software_in_aci_mode 15.2(6h)
  - nx-os_system_software_in_aci_mode 16.0(1j)
  - nx-os_system_software_in_aci_mode 15.2(6g)
  - nx-os_system_software_in_aci_mode 15.2(7f)
  - nx-os_system_software_in_aci_mode 15.2(7g)
  - nx-os_system_software_in_aci_mode 16.0(2h)
  - nx-os_system_software_in_aci_mode 15.2(8d)
  - nx-os_system_software_in_aci_mode 16.0(2j)
  - nx-os_system_software_in_aci_mode 15.2(8e)
  - nx-os_system_software_in_aci_mode 16.0(3d)
  - nx-os_system_software_in_aci_mode 16.0(3e)
  - nx-os_system_software_in_aci_mode 15.2(8f)
  - nx-os_system_software_in_aci_mode 15.2(8g)
  - nx-os_system_software_in_aci_mode 15.3(1d)
  - nx-os_system_software_in_aci_mode 15.2(8h)
  - nx-os_system_software_in_aci_mode 16.0(4c)
  - nx-os_system_software_in_aci_mode 15.3(2a)
  - nx-os_system_software_in_aci_mode 15.2(8i)
  - nx-os_system_software_in_aci_mode 16.0(5h)
  - nx-os_system_software_in_aci_mode 15.3(2b)
  - nx-os_system_software_in_aci_mode 16.0(3g)
  - nx-os_system_software_in_aci_mode 16.0(5j)
  - nx-os_system_software_in_aci_mode 15.3(2c)
  - nx-os_system_software_in_aci_mode 16.0(6c)
  - nx-os_system_software_in_aci_mode 15.3(2d)
  - nx-os_system_software_in_aci_mode 16.1(1f)
  - nx-os_system_software_in_aci_mode 16.0(7e)
  - nx-os_system_software_in_aci_mode 16.0(8e)
  - nx-os_system_software_in_aci_mode 15.3(2e)
  - nx-os_system_software_in_aci_mode 16.0(8f)
  - nx-os_system_software_in_aci_mode 16.1(2f)
  - nx-os_system_software_in_aci_mode 16.1(2g)
  - nx-os_system_software_in_aci_mode 15.3(2f)
  - nx-os_system_software_in_aci_mode 16.0(9c)
published: '2026-10-07'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T17:16:54.690'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20038'
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-epgcbp-SfDU7NLf
    label: psirt@cisco.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-07T16:38:22.256Z'
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-07T18:02:43.242313Z'
---

## Overview

A vulnerability in the endpoint group (EPG) contract functionality of Cisco Nexus 9000 Series Fabric Switches in ACI Mode could allow an unauthenticated, remote attacker to bypass configured EPG contracts.

This vulnerability is due to an improper control with EPG contracts. An attacker could exploit this vulnerability by sending IPv4 or IPv6 packets using UDP source and destination ports that are assigned to DHCP traffic through an affected device. A successful exploit could allow the attacker to bypass EPG contracts on the affected device.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.