FKIE_CVE-2026-20038
Vulnerability from fkie_nvd - Published: 2026-10-07 17:16 - Updated: 2026-10-08 20:08
Severity
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.
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unknown",
"product": "Cisco NX-OS System Software in ACI Mode",
"vendor": "Cisco",
"versions": [
{
"status": "affected",
"version": "15.2(1g)"
},
{
"status": "affected",
"version": "15.2(2e)"
},
{
"status": "affected",
"version": "15.2(2f)"
},
{
"status": "affected",
"version": "15.2(2g)"
},
{
"status": "affected",
"version": "15.2(2h)"
},
{
"status": "affected",
"version": "15.2(3f)"
},
{
"status": "affected",
"version": "15.2(3e)"
},
{
"status": "affected",
"version": "15.2(3g)"
},
{
"status": "affected",
"version": "15.2(4d)"
},
{
"status": "affected",
"version": "15.2(4e)"
},
{
"status": "affected",
"version": "15.2(5c)"
},
{
"status": "affected",
"version": "15.2(5d)"
},
{
"status": "affected",
"version": "16.0(1g)"
},
{
"status": "affected",
"version": "15.2(5e)"
},
{
"status": "affected",
"version": "15.2(4f)"
},
{
"status": "affected",
"version": "15.2(6e)"
},
{
"status": "affected",
"version": "15.2(6h)"
},
{
"status": "affected",
"version": "16.0(1j)"
},
{
"status": "affected",
"version": "15.2(6g)"
},
{
"status": "affected",
"version": "15.2(7f)"
},
{
"status": "affected",
"version": "15.2(7g)"
},
{
"status": "affected",
"version": "16.0(2h)"
},
{
"status": "affected",
"version": "15.2(8d)"
},
{
"status": "affected",
"version": "16.0(2j)"
},
{
"status": "affected",
"version": "15.2(8e)"
},
{
"status": "affected",
"version": "16.0(3d)"
},
{
"status": "affected",
"version": "16.0(3e)"
},
{
"status": "affected",
"version": "15.2(8f)"
},
{
"status": "affected",
"version": "15.2(8g)"
},
{
"status": "affected",
"version": "15.3(1d)"
},
{
"status": "affected",
"version": "15.2(8h)"
},
{
"status": "affected",
"version": "16.0(4c)"
},
{
"status": "affected",
"version": "15.3(2a)"
},
{
"status": "affected",
"version": "15.2(8i)"
},
{
"status": "affected",
"version": "16.0(5h)"
},
{
"status": "affected",
"version": "15.3(2b)"
},
{
"status": "affected",
"version": "16.0(3g)"
},
{
"status": "affected",
"version": "16.0(5j)"
},
{
"status": "affected",
"version": "15.3(2c)"
},
{
"status": "affected",
"version": "16.0(6c)"
},
{
"status": "affected",
"version": "15.3(2d)"
},
{
"status": "affected",
"version": "16.1(1f)"
},
{
"status": "affected",
"version": "16.0(7e)"
},
{
"status": "affected",
"version": "16.0(8e)"
},
{
"status": "affected",
"version": "15.3(2e)"
},
{
"status": "affected",
"version": "16.0(8f)"
},
{
"status": "affected",
"version": "16.1(2f)"
},
{
"status": "affected",
"version": "16.1(2g)"
},
{
"status": "affected",
"version": "15.3(2f)"
},
{
"status": "affected",
"version": "16.0(9c)"
},
{
"status": "affected",
"version": "16.1(3f)"
},
{
"status": "affected",
"version": "16.0(9d)"
},
{
"status": "affected",
"version": "16.0(6h)"
},
{
"status": "affected",
"version": "16.0(8h)"
},
{
"status": "affected",
"version": "16.1(3g)"
},
{
"status": "affected",
"version": "16.0(9e)"
},
{
"status": "affected",
"version": "16.1(4h)"
},
{
"status": "affected",
"version": "16.1(5e)"
},
{
"status": "affected",
"version": "16.2(1g)"
},
{
"status": "affected",
"version": "16.0(9f)"
},
{
"status": "affected",
"version": "16.2(2e)"
}
]
}
],
"source": "psirt@cisco.com"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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 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\u0026nbsp;DHCP traffic through an affected device. A successful exploit could allow the attacker to bypass EPG contracts on the affected device."
}
],
"id": "CVE-2026-20038",
"lastModified": "2026-10-08T20:08:45.857",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 1.4,
"source": "psirt@cisco.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-20038",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-07T18:02:43.242313Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-10-07T17:16:54.690",
"references": [
{
"source": "psirt@cisco.com",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-epgcbp-SfDU7NLf"
}
],
"sourceIdentifier": "psirt@cisco.com",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-284"
}
],
"source": "psirt@cisco.com",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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