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CVE-2020-12820

Estado: AnalizadaAlta (8.8)—

Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Buffer overflow (CWE-787) en servicio remoto SSL VPN que requiere autenticación (PR:L, AV:N). Permite ejecución de código arbitrario o DoS. T1210 por acceso remoto con privilegios; T1059 por ejecución de código; T1499.004 (crash) por potencial DoS confirmado.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account ManagementDisable or Remove Feature or ProgramVulnerability ScanningThreat Intelligence ProgramRestrict Web-Based ContentNetwork Segmentation

Tecnologías afectadas (1)

Fortinet — Fortios

CWE

Referencias

JSON original (NVD)

Mostrar
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          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "none"
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            {
              "automatable": "no"
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            {
              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2024-12-20T17:24:49.607607Z"
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  },
  "affected": [
    {
      "source": "psirt@fortinet.com",
      "affectedData": [
        {
          "cpes": [
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            "cpe:2.3:o:fortinet:fortios:6.0.8:*:*:*:*:*:*:*",
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          "vendor": "Fortinet",
          "product": "FortiOS",
          "versions": [
            {
              "status": "affected",
              "version": "6.0.0",
              "versionType": "semver",
              "lessThanOrEqual": "6.0.10"
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  "published": "2024-12-19T11:15:05.700",
  "references": [
    {
      "url": "https://fortiguard.fortinet.com/psirt/FG-IR-20-083",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "psirt@fortinet.com"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "type": "Secondary",
      "source": "psirt@fortinet.com",
      "description": [
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          "value": "CWE-121"
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    },
    {
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      "value": "En una configuración no predeterminada, un desbordamiento de búfer basado en pila en FortiOS versión 6.0.10 y anteriores, versión 5.6.12 y anteriores puede permitir que un atacante remoto autenticado en la VPN SSL bloquee el daemon NAC de FortiClient (fcnacd) y potencialmente ejecute código arbitrario mediante la solicitud de un nombre de archivo FortiClient grande. No tenemos conocimiento de ningún código de prueba de concepto que logre esto último con éxito."
    }
  ],
  "lastModified": "2026-06-17T02:52:22.410",
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