CVE-2026-20038

Cisco Nexus 9000 Series Fabric Switches in ACI Mode Policy-Based Redirect Endpoint Group Contract Bypass Vulnerability

Published Oct 7, 2026 CVSS 3.1 · 5.8 Medium EPSS < 1% KEV · Not listed

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Cisco

Cisco NX-OS System Software in ACI Mode

unknown

Version	Status	Constraints
`15.2(1g)`	affected	—
`15.2(2e)`	affected	—
`15.2(2f)`	affected	—
`15.2(2g)`	affected	—
`15.2(2h)`	affected	—
`15.2(3f)`	affected	—
`15.2(3e)`	affected	—
`15.2(3g)`	affected	—
`15.2(4d)`	affected	—
`15.2(4e)`	affected	—
`15.2(5c)`	affected	—
`15.2(5d)`	affected	—
`16.0(1g)`	affected	—
`15.2(5e)`	affected	—
`15.2(4f)`	affected	—
`15.2(6e)`	affected	—
`15.2(6h)`	affected	—
`16.0(1j)`	affected	—
`15.2(6g)`	affected	—
`15.2(7f)`	affected	—
`15.2(7g)`	affected	—
`16.0(2h)`	affected	—
`15.2(8d)`	affected	—
`16.0(2j)`	affected	—
`15.2(8e)`	affected	—
`16.0(3d)`	affected	—
`16.0(3e)`	affected	—
`15.2(8f)`	affected	—
`15.2(8g)`	affected	—
`15.3(1d)`	affected	—
`15.2(8h)`	affected	—
`16.0(4c)`	affected	—
`15.3(2a)`	affected	—
`15.2(8i)`	affected	—
`16.0(5h)`	affected	—
`15.3(2b)`	affected	—
`16.0(3g)`	affected	—
`16.0(5j)`	affected	—
`15.3(2c)`	affected	—
`16.0(6c)`	affected	—
`15.3(2d)`	affected	—
`16.1(1f)`	affected	—
`16.0(7e)`	affected	—
`16.0(8e)`	affected	—
`15.3(2e)`	affected	—
`16.0(8f)`	affected	—
`16.1(2f)`	affected	—
`16.1(2g)`	affected	—
`15.3(2f)`	affected	—
`16.0(9c)`	affected	—
`16.1(3f)`	affected	—
`16.0(9d)`	affected	—
`16.0(6h)`	affected	—
`16.0(8h)`	affected	—
`16.1(3g)`	affected	—
`16.0(9e)`	affected	—
`16.1(4h)`	affected	—
`16.1(5e)`	affected	—
`16.2(1g)`	affected	—
`16.0(9f)`	affected	—
`16.2(2e)`	affected	—

No data.

Vendor Product Versions

Cisco

Cisco Nx-os System Software In Aci Mode

Version	Status	Scheme	Platform
`[15.2(1g),15.2(1g)]`	affected	generic	—
`[15.2(2e),15.2(2e)]`	affected	generic	—
`[15.2(2f),15.2(2f)]`	affected	generic	—
`[15.2(2g),15.2(2g)]`	affected	generic	—
`[15.2(2h),15.2(2h)]`	affected	generic	—
`[15.2(3f),15.2(3f)]`	affected	generic	—
`[15.2(3e),15.2(3e)]`	affected	generic	—
`[15.2(3g),15.2(3g)]`	affected	generic	—
`[15.2(4d),15.2(4d)]`	affected	generic	—
`[15.2(4e),15.2(4e)]`	affected	generic	—
`[15.2(5c),15.2(5c)]`	affected	generic	—
`[15.2(5d),15.2(5d)]`	affected	generic	—
`[16.0(1g),16.0(1g)]`	affected	generic	—
`[15.2(5e),15.2(5e)]`	affected	generic	—
`[15.2(4f),15.2(4f)]`	affected	generic	—
`[15.2(6e),15.2(6e)]`	affected	generic	—
`[15.2(6h),15.2(6h)]`	affected	generic	—
`[16.0(1j),16.0(1j)]`	affected	generic	—
`[15.2(6g),15.2(6g)]`	affected	generic	—
`[15.2(7f),15.2(7f)]`	affected	generic	—
`[15.2(7g),15.2(7g)]`	affected	generic	—
`[16.0(2h),16.0(2h)]`	affected	generic	—
`[15.2(8d),15.2(8d)]`	affected	generic	—
`[16.0(2j),16.0(2j)]`	affected	generic	—
`[15.2(8e),15.2(8e)]`	affected	generic	—
`[16.0(3d),16.0(3d)]`	affected	generic	—
`[16.0(3e),16.0(3e)]`	affected	generic	—
`[15.2(8f),15.2(8f)]`	affected	generic	—
`[15.2(8g),15.2(8g)]`	affected	generic	—
`[15.3(1d),15.3(1d)]`	affected	generic	—
`[15.2(8h),15.2(8h)]`	affected	generic	—
`[16.0(4c),16.0(4c)]`	affected	generic	—
`[15.3(2a),15.3(2a)]`	affected	generic	—
`[15.2(8i),15.2(8i)]`	affected	generic	—
`[16.0(5h),16.0(5h)]`	affected	generic	—
`[15.3(2b),15.3(2b)]`	affected	generic	—
`[16.0(3g),16.0(3g)]`	affected	generic	—
`[16.0(5j),16.0(5j)]`	affected	generic	—
`[15.3(2c),15.3(2c)]`	affected	generic	—
`[16.0(6c),16.0(6c)]`	affected	generic	—
`[15.3(2d),15.3(2d)]`	affected	generic	—
`[16.1(1f),16.1(1f)]`	affected	generic	—
`[16.0(7e),16.0(7e)]`	affected	generic	—
`[16.0(8e),16.0(8e)]`	affected	generic	—
`[15.3(2e),15.3(2e)]`	affected	generic	—
`[16.0(8f),16.0(8f)]`	affected	generic	—
`[16.1(2f),16.1(2f)]`	affected	generic	—
`[16.1(2g),16.1(2g)]`	affected	generic	—
`[15.3(2f),15.3(2f)]`	affected	generic	—
`[16.0(9c),16.0(9c)]`	affected	generic	—
`[16.1(3f),16.1(3f)]`	affected	generic	—
`[16.0(9d),16.0(9d)]`	affected	generic	—
`[16.0(6h),16.0(6h)]`	affected	generic	—
`[16.0(8h),16.0(8h)]`	affected	generic	—
`[16.1(3g),16.1(3g)]`	affected	generic	—
`[16.0(9e),16.0(9e)]`	affected	generic	—
`[16.1(4h),16.1(4h)]`	affected	generic	—
`[16.1(5e),16.1(5e)]`	affected	generic	—
`[16.2(1g),16.2(1g)]`	affected	generic	—
`[16.0(9f),16.0(9f)]`	affected	generic	—
`[16.2(2e),16.2(2e)]`	affected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact None

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.301% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact partial

References

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

History

Oct 7, 2026 7:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Oct 7, 2026 6:30 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Cisco Cisco cisco Nx-os System Software In Aci Mode
Vendors & Products		Cisco Cisco cisco Nx-os System Software In Aci Mode

Oct 7, 2026 4:30 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
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.
Title		Cisco Nexus 9000 Series Fabric Switches in ACI Mode Policy-Based Redirect Endpoint Group Contract Bypass Vulnerability
Weaknesses		CWE-284
References		https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-epgcbp-SfDU7NLf
Metrics		cvssV3_1 `{'score': 5.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N'}`