FKIE_CVE-2026-20051

Vulnerability from fkie_nvd - Published: 2026-02-25 17:25 - Updated: 2026-04-15 00:35
Severity ?
7.4 (High) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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. 
References
psirt@cisco.comhttps://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-ether-dos-Kv8YNWZ4
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "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;"
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad en el procesamiento de paquetes de entrada de Capa 2 de Ethernet VPN (EVPN) de los switches de plataforma Cisco Nexus 3600 y las plataformas de switching Cisco Nexus 9500-R Series podr\u00eda permitir a un atacante adyacente no autenticado desencadenar un bucle de tr\u00e1fico de Capa 2.\n\nEsta vulnerabilidad se debe a un error de l\u00f3gica al procesar una trama de entrada de Capa 2 manipulada. Un atacante podr\u00eda explotar esta vulnerabilidad enviando un flujo de tramas Ethernet manipuladas a trav\u00e9s del dispositivo objetivo. Un exploit exitoso podr\u00eda permitir al atacante causar un bucle de tr\u00e1fico de Capa 2 de Virtual eXtensible LAN (VxLAN), lo que, a su vez, podr\u00eda resultar en una condici\u00f3n de denegaci\u00f3n de servicio (DoS). Este bucle de Capa 2 podr\u00eda sobresaturar el ancho de banda en las interfaces de red, lo que resultar\u00eda en la ca\u00edda de todo el tr\u00e1fico del plano de datos. Para explotar esta vulnerabilidad, el atacante debe ser adyacente en Capa 2 al dispositivo afectado.\nNota: Para detener la explotaci\u00f3n activa de esta vulnerabilidad, se requiere intervenci\u00f3n manual tanto para detener el tr\u00e1fico manipulado como para reiniciar todas las interfaces de red involucradas. Para asistencia adicional si se sospecha de un bucle de Capa 2 relacionado con esta vulnerabilidad, contacte con el Centro de Asistencia T\u00e9cnica de Cisco (TAC) o con el proveedor de soporte adecuado."
    }
  ],
  "id": "CVE-2026-20051",
  "lastModified": "2026-04-15T00:35:42.020",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "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"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.0,
        "source": "psirt@cisco.com",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-02-25T17:25:26.487",
  "references": [
    {
      "source": "psirt@cisco.com",
      "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-ether-dos-Kv8YNWZ4"
    }
  ],
  "sourceIdentifier": "psirt@cisco.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-457"
        }
      ],
      "source": "psirt@cisco.com",
      "type": "Primary"
    }
  ]
}


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