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Cisco Nexus 9000 CVE-2026-20038

| EUVDEUVD-2026-94446 MEDIUM
Improper Access Control (CWE-284)
2026-10-07 cisco GHSA-8r87-mj76-xw8h
5.8
CVSS 3.1 · Vendor: cisco
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Severity by source

Vendor (cisco) PRIMARY
5.8 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
vuln.today AI
5.8 MEDIUM

Unauthenticated network packets (AV:N/PR:N/UI:N/AC:L) defeat policy enforced for other endpoints, so S:C with I:L only; no confidentiality or availability loss.

3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

Primary rating from Vendor (cisco).

CVSS VectorVendor: cisco

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

Lifecycle Timeline

2
Analysis Generated
Oct 07, 2026 - 17:16 vuln.today
CVE Published
Oct 07, 2026 - 16:11 cve.org
MEDIUM 5.8

DescriptionCVE.org

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.

AnalysisAI

EPG contract bypass in Cisco Nexus 9000 Series Fabric Switches running ACI Mode allows an unauthenticated, remote attacker to evade configured endpoint-group segmentation by sending IPv4 or IPv6 UDP packets with DHCP source and destination ports (67/68) through the device. The flaw is an improper access-control implementation (CWE-284) rated CVSS 5.8 with scope change and low integrity impact; no public exploit identified at time of analysis. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
technique details hidden
Exploit
technique details hidden
Execution
technique details hidden
Impact
technique details hidden

Vulnerability AssessmentAI

Exploitation Exploitation requires that the affected Cisco Nexus 9000 switch be running in ACI mode and be configured to enforce EPG contracts for traffic segmentation; the attacker must be able to send packets through the device and specifically must use UDP source and destination ports assigned to DHCP traffic (67/68) within IPv4 or IPv6 packets to trigger the improper contract handling. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a moderate-severity access-control weakness (CVSS 5.8, CWE-284) that should be treated as a configuration-integrity/segmentation-bypass issue rather than a system-compromise priority. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Patch status is not specified in the provided data; consult Cisco's advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-epgcbp-SfDU7NLf for fixed NX-OS in ACI mode releases and upgrade instructions. … Detailed patch versions, workarounds, and compensating controls in full report.

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CVE-2026-20038 vulnerability details – vuln.today

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