Vulnerability-Lookup

GHSA-4466-83Q5-3RXW

Vulnerability from github – Published: 2026-02-25 18:31 – Updated: 2026-02-25 18:31

Details

This vulnerability is due to a logic error when processing a crafted Layer 2 ingress frame. An attacker could exploit this vulnerability by sending a stream of crafted Ethernet frames through the targeted device. A successful exploit could allow the attacker to cause a Layer 2 Virtual eXtensible LAN (VxLAN) traffic loop, which, in turn, could result in a denial of service (DoS) condition. This Layer 2 loop could oversubscribe the bandwidth on network interfaces, which would result in all data plane traffic being dropped. To exploit this vulnerability, the attacker must be Layer 2-adjacent to the affected device. Note: To stop active exploitation of this vulnerability, manual intervention is required to both stop the crafted traffic and flap all involved network interfaces. For additional assistance if a Layer 2 loop that is related to this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or the proper support provider.

Severity

7.4 (High)


                  
                    CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-20051"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-457"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-25T17:25:26Z",
    "severity": "HIGH"
  },
  "details": "A vulnerability with the Ethernet VPN (EVPN) Layer 2 ingress packet processing of Cisco Nexus 3600 Platform Switches and Cisco Nexus 9500-R Series Switching Platforms could allow an unauthenticated, adjacent attacker to trigger a Layer 2 traffic loop.\n\nThis vulnerability is due to a logic error when processing a crafted Layer 2 ingress frame. An attacker could exploit this vulnerability by sending a stream of crafted Ethernet frames through the targeted device. A successful exploit could allow the attacker to cause a Layer 2 Virtual eXtensible LAN (VxLAN) traffic loop, which, in turn, could result in a denial of service (DoS) condition. This Layer 2 loop could oversubscribe the bandwidth on network interfaces, which would result in all data plane traffic being dropped. To exploit this vulnerability, the attacker must be Layer 2-adjacent to the affected device.\nNote:\u0026nbsp;To stop active exploitation of this vulnerability, manual intervention is required to both stop the crafted traffic and flap all involved network interfaces. For additional assistance if a Layer 2 loop that is related to this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or the proper support provider.\u0026nbsp;",
  "id": "GHSA-4466-83q5-3rxw",
  "modified": "2026-02-25T18:31:38Z",
  "published": "2026-02-25T18:31:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-20051"
    },
    {
      "type": "WEB",
      "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-ether-dos-Kv8YNWZ4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-20051 (GCVE-0-2026-20051)

Vulnerability from cvelistv5 – Published: 2026-02-25 16:14 – Updated: 2026-02-25 19:05

Title

Cisco Nexus 3600-R and 9500-R Series Switching Platforms Layer 2 Loop Denial of Service Vulnerability

Summary

A vulnerability with the Ethernet VPN (EVPN) Layer 2 ingress packet processing of Cisco Nexus 3600 Platform Switches and Cisco Nexus 9500-R Series Switching Platforms could allow an unauthenticated, adjacent attacker to trigger a Layer 2 traffic loop. This vulnerability is due to a logic error when processing a crafted Layer 2 ingress frame. An attacker could exploit this vulnerability by sending a stream of crafted Ethernet frames through the targeted device. A successful exploit could allow the attacker to cause a Layer 2 Virtual eXtensible LAN (VxLAN) traffic loop, which, in turn, could result in a denial of service (DoS) condition. This Layer 2 loop could oversubscribe the bandwidth on network interfaces, which would result in all data plane traffic being dropped. To exploit this vulnerability, the attacker must be Layer 2-adjacent to the affected device. Note: To stop active exploitation of this vulnerability, manual intervention is required to both stop the crafted traffic and flap all involved network interfaces. For additional assistance if a Layer 2 loop that is related to this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or the proper support provider.

Severity

7.4 (High)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-02-25 18:18 UTC

CWE

CWE-457 - Use of Uninitialized Variable

Assigner

cisco mitre root

References

1 reference

URL	Tags
https://sec.cloudapps.cisco.com/security/center/c…

Impacted products

1 product

Vendor	Product	Version
Cisco	Cisco NX-OS Software	Affected: 9.2(3) Affected: 9.2(2v) Affected: 9.2(1) Affected: 9.2(2t) Affected: 9.2(3y) Affected: 9.3(2) Affected: 9.2(4) Affected: 9.3(1) Affected: 9.3(1z) Affected: 9.2(2) Affected: 9.3(3) Affected: 9.3(4) Affected: 9.3(5) Affected: 9.3(6) Affected: 9.3(5w) Affected: 9.3(7) Affected: 9.3(7k) Affected: 10.2(1) Affected: 9.3(7a) Affected: 9.3(8) Affected: 10.2(1q) Affected: 10.2(2) Affected: 9.3(9) Affected: 10.2(3) Affected: 10.2(3t) Affected: 9.3(10) Affected: 10.2(2a) Affected: 10.3(1) Affected: 10.2(4) Affected: 10.3(2) Affected: 9.3(11) Affected: 10.3(3) Affected: 10.2(5) Affected: 9.3(12) Affected: 10.2(3v) Affected: 10.4(1) Affected: 10.2(6) Affected: 10.3(3w) Affected: 10.3(3o) Affected: 10.3(4) Affected: 10.3(3p) Affected: 10.3(4a) Affected: 10.4(2) Affected: 10.3(3q) Affected: 9.3(13) Affected: 10.3(5) Affected: 10.2(7) Affected: 10.4(3) Affected: 10.3(3x) Affected: 10.3(4g) Affected: 10.5(1) Affected: 10.2(8) Affected: 10.3(3r) Affected: 10.3(6) Affected: 9.3(14) Affected: 10.4(4) Affected: 10.3(4h) Affected: 10.5(2) Affected: 10.3(7) Affected: 10.4(5) Affected: 10.5(3) Affected: 10.2(9) Affected: 9.3(15) Affected: 10.4(4g) Affected: 10.5(4) Affected: 10.6(1) Affected: 10.5(3t) Affected: 10.3(8) Affected: 10.4(6) Affected: 10.5(3s) Affected: 10.5(3e) Affected: 10.5(3o) Affected: 9.3(16) Affected: 10.6(1s) Affected: 10.5(3p)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-20051",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-25T18:18:59.463626Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-02-25T19:05:49.650Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "product": "Cisco NX-OS Software",
          "vendor": "Cisco",
          "versions": [
            {
              "status": "affected",
              "version": "9.2(3)"
            },
            {
              "status": "affected",
              "version": "9.2(2v)"
            },
            {
              "status": "affected",
              "version": "9.2(1)"
            },
            {
              "status": "affected",
              "version": "9.2(2t)"
            },
            {
              "status": "affected",
              "version": "9.2(3y)"
            },
            {
              "status": "affected",
              "version": "9.3(2)"
            },
            {
              "status": "affected",
              "version": "9.2(4)"
            },
            {
              "status": "affected",
              "version": "9.3(1)"
            },
            {
              "status": "affected",
              "version": "9.3(1z)"
            },
            {
              "status": "affected",
              "version": "9.2(2)"
            },
            {
              "status": "affected",
              "version": "9.3(3)"
            },
            {
              "status": "affected",
              "version": "9.3(4)"
            },
            {
              "status": "affected",
              "version": "9.3(5)"
            },
            {
              "status": "affected",
              "version": "9.3(6)"
            },
            {
              "status": "affected",
              "version": "9.3(5w)"
            },
            {
              "status": "affected",
              "version": "9.3(7)"
            },
            {
              "status": "affected",
              "version": "9.3(7k)"
            },
            {
              "status": "affected",
              "version": "10.2(1)"
            },
            {
              "status": "affected",
              "version": "9.3(7a)"
            },
            {
              "status": "affected",
              "version": "9.3(8)"
            },
            {
              "status": "affected",
              "version": "10.2(1q)"
            },
            {
              "status": "affected",
              "version": "10.2(2)"
            },
            {
              "status": "affected",
              "version": "9.3(9)"
            },
            {
              "status": "affected",
              "version": "10.2(3)"
            },
            {
              "status": "affected",
              "version": "10.2(3t)"
            },
            {
              "status": "affected",
              "version": "9.3(10)"
            },
            {
              "status": "affected",
              "version": "10.2(2a)"
            },
            {
              "status": "affected",
              "version": "10.3(1)"
            },
            {
              "status": "affected",
              "version": "10.2(4)"
            },
            {
              "status": "affected",
              "version": "10.3(2)"
            },
            {
              "status": "affected",
              "version": "9.3(11)"
            },
            {
              "status": "affected",
              "version": "10.3(3)"
            },
            {
              "status": "affected",
              "version": "10.2(5)"
            },
            {
              "status": "affected",
              "version": "9.3(12)"
            },
            {
              "status": "affected",
              "version": "10.2(3v)"
            },
            {
              "status": "affected",
              "version": "10.4(1)"
            },
            {
              "status": "affected",
              "version": "10.2(6)"
            },
            {
              "status": "affected",
              "version": "10.3(3w)"
            },
            {
              "status": "affected",
              "version": "10.3(3o)"
            },
            {
              "status": "affected",
              "version": "10.3(4)"
            },
            {
              "status": "affected",
              "version": "10.3(3p)"
            },
            {
              "status": "affected",
              "version": "10.3(4a)"
            },
            {
              "status": "affected",
              "version": "10.4(2)"
            },
            {
              "status": "affected",
              "version": "10.3(3q)"
            },
            {
              "status": "affected",
              "version": "9.3(13)"
            },
            {
              "status": "affected",
              "version": "10.3(5)"
            },
            {
              "status": "affected",
              "version": "10.2(7)"
            },
            {
              "status": "affected",
              "version": "10.4(3)"
            },
            {
              "status": "affected",
              "version": "10.3(3x)"
            },
            {
              "status": "affected",
              "version": "10.3(4g)"
            },
            {
              "status": "affected",
              "version": "10.5(1)"
            },
            {
              "status": "affected",
              "version": "10.2(8)"
            },
            {
              "status": "affected",
              "version": "10.3(3r)"
            },
            {
              "status": "affected",
              "version": "10.3(6)"
            },
            {
              "status": "affected",
              "version": "9.3(14)"
            },
            {
              "status": "affected",
              "version": "10.4(4)"
            },
            {
              "status": "affected",
              "version": "10.3(4h)"
            },
            {
              "status": "affected",
              "version": "10.5(2)"
            },
            {
              "status": "affected",
              "version": "10.3(7)"
            },
            {
              "status": "affected",
              "version": "10.4(5)"
            },
            {
              "status": "affected",
              "version": "10.5(3)"
            },
            {
              "status": "affected",
              "version": "10.2(9)"
            },
            {
              "status": "affected",
              "version": "9.3(15)"
            },
            {
              "status": "affected",
              "version": "10.4(4g)"
            },
            {
              "status": "affected",
              "version": "10.5(4)"
            },
            {
              "status": "affected",
              "version": "10.6(1)"
            },
            {
              "status": "affected",
              "version": "10.5(3t)"
            },
            {
              "status": "affected",
              "version": "10.3(8)"
            },
            {
              "status": "affected",
              "version": "10.4(6)"
            },
            {
              "status": "affected",
              "version": "10.5(3s)"
            },
            {
              "status": "affected",
              "version": "10.5(3e)"
            },
            {
              "status": "affected",
              "version": "10.5(3o)"
            },
            {
              "status": "affected",
              "version": "9.3(16)"
            },
            {
              "status": "affected",
              "version": "10.6(1s)"
            },
            {
              "status": "affected",
              "version": "10.5(3p)"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "A vulnerability with the Ethernet VPN (EVPN) Layer 2 ingress packet processing of Cisco Nexus 3600 Platform Switches and Cisco Nexus 9500-R Series Switching Platforms could allow an unauthenticated, adjacent attacker to trigger a Layer 2 traffic loop.\r\n\r\nThis vulnerability is due to a logic error when processing a crafted Layer 2 ingress frame. An attacker could exploit this vulnerability by sending a stream of crafted Ethernet frames through the targeted device. A successful exploit could allow the attacker to cause a Layer 2 Virtual eXtensible LAN (VxLAN) traffic loop, which, in turn, could result in a denial of service (DoS) condition. This Layer 2 loop could oversubscribe the bandwidth on network interfaces, which would result in all data plane traffic being dropped. To exploit this vulnerability, the attacker must be Layer 2-adjacent to the affected device.\r\nNote:\u0026nbsp;To stop active exploitation of this vulnerability, manual intervention is required to both stop the crafted traffic and flap all involved network interfaces. For additional assistance if a Layer 2 loop that is related to this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or the proper support provider.\u0026nbsp;"
        }
      ],
      "exploits": [
        {
          "lang": "en",
          "value": "The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "cvssV3_1"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-457",
              "description": "Use of Uninitialized Variable",
              "lang": "en",
              "type": "cwe"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-25T16:14:33.859Z",
        "orgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
        "shortName": "cisco"
      },
      "references": [
        {
          "name": "cisco-sa-nxos-ether-dos-Kv8YNWZ4",
          "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-ether-dos-Kv8YNWZ4"
        }
      ],
      "source": {
        "advisory": "cisco-sa-nxos-ether-dos-Kv8YNWZ4",
        "defects": [
          "CSCwo94451"
        ],
        "discovery": "EXTERNAL"
      },
      "title": "Cisco Nexus 3600-R and 9500-R Series Switching Platforms Layer 2 Loop Denial of Service Vulnerability"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
    "assignerShortName": "cisco",
    "cveId": "CVE-2026-20051",
    "datePublished": "2026-02-25T16:14:33.859Z",
    "dateReserved": "2025-10-08T11:59:15.355Z",
    "dateUpdated": "2026-02-25T19:05:49.650Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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.

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.