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CVE-2023-20270

Status: ModifiedMedium (5.8)—

A vulnerability in the interaction between the Server Message Block (SMB) protocol preprocessor and the Snort 3 detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the configured policies or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper error-checking when the Snort 3 detection engine is processing SMB traffic. An attacker could exploit this vulnerability by sending a crafted SMB packet stream through an affected device. A successful exploit could allow the attacker to cause the Snort process to reload, resulting in a DoS condition.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Cisco — Secure Firewall Threat Defense

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2023-20270",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
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        "type": "Secondary",
        "source": "psirt@cisco.com",
        "cvssData": {
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          "version": "3.1",
          "baseScore": 5.8,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "LOW",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 3.9
      },
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "LOW",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
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        "exploitabilityScore": 3.9
      }
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  },
  "affected": [
    {
      "source": "psirt@cisco.com",
      "affectedData": [
        {
          "vendor": "Cisco",
          "product": "Cisco Firepower Threat Defense Software",
          "versions": [
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              "status": "affected",
              "version": "7.1.0"
            },
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              "status": "affected",
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              "version": "7.1.0.2"
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              "version": "7.1.0.3"
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            {
              "status": "affected",
              "version": "7.2.0"
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            {
              "status": "affected",
              "version": "7.2.0.1"
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            {
              "status": "affected",
              "version": "7.2.1"
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              "status": "affected",
              "version": "7.2.2"
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              "status": "affected",
              "version": "7.2.3"
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              "status": "affected",
              "version": "7.3.0"
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            {
              "status": "affected",
              "version": "7.3.1"
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  ],
  "published": "2023-11-01T17:15:11.783",
  "references": [
    {
      "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-smbsnort3-dos-pfOjOYUV",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "psirt@cisco.com"
    },
    {
      "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-smbsnort3-dos-pfOjOYUV",
      "tags": [
        "Vendor Advisory"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "psirt@cisco.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-20"
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    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
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    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability in the interaction between the Server Message Block (SMB) protocol preprocessor and the Snort 3 detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the configured policies or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper error-checking when the Snort 3 detection engine is processing SMB traffic. An attacker could exploit this vulnerability by sending a crafted SMB packet stream through an affected device. A successful exploit could allow the attacker to cause the Snort process to reload, resulting in a DoS condition."
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad en la interacción entre el preprocesador del protocolo Server Message Block (SMB) y el motor de detección Snort 3 para el software Cisco Firepower Threat Defense (FTD) podría permitir que un atacante remoto no autenticado omita las políticas configuradas o provoque una Denegación de Servicio (DoS) condición en un dispositivo afectado. Esta vulnerabilidad se debe a una verificación de errores incorrecta cuando el motor de detección de Snort 3 procesa el tráfico SMB. Un atacante podría aprovechar esta vulnerabilidad enviando un flujo de paquetes SMB manipulado a través de un dispositivo afectado. Un exploit exitoso podría permitir al atacante hacer que el proceso Snort se recargue, lo que resultaría en una condición DoS."
    }
  ],
  "lastModified": "2026-08-11T19:33:44.513",
  "configurations": [
    {
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        {
          "negate": false,
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          "operator": "OR"
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  "sourceIdentifier": "psirt@cisco.com"
}