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CVE-2020-1999

Status: ModifiedMedium (5.3)—

A vulnerability exists in the Palo Alto Network PAN-OS signature-based threat detection engine that allows an attacker to communicate with devices in the network in a way that is not analyzed for threats by sending data through specifically crafted TCP packets. This technique evades signature-based threat detection. This issue impacts: PAN-OS 8.1 versions earlier than 8.1.17; PAN-OS 9.0 versions earlier than 9.0.11; PAN-OS 9.1 versions earlier than 9.1.5; All versions of PAN-OS 7.1 and PAN-OS 8.0.

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)

Paloaltonetworks — Pan-os

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2020-1999",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:N/I:P/A:N",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "psirt@paloaltonetworks.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 3.9
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "psirt@paloaltonetworks.com",
      "affectedData": [
        {
          "vendor": "Palo Alto Networks",
          "product": "PAN-OS",
          "versions": [
            {
              "status": "affected",
              "version": "7.1.*"
            },
            {
              "status": "affected",
              "version": "8.0.*"
            },
            {
              "status": "unaffected",
              "version": "10.0.*"
            },
            {
              "status": "affected",
              "changes": [
                {
                  "at": "8.1.17",
                  "status": "unaffected"
                }
              ],
              "version": "8.1",
              "lessThan": "8.1.17",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "changes": [
                {
                  "at": "9.0.11",
                  "status": "unaffected"
                }
              ],
              "version": "9.0",
              "lessThan": "9.0.11",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "changes": [
                {
                  "at": "9.1.5",
                  "status": "unaffected"
                }
              ],
              "version": "9.1",
              "lessThan": "9.1.5",
              "versionType": "custom"
            }
          ]
        }
      ]
    }
  ],
  "published": "2020-11-12T00:15:10.253",
  "references": [
    {
      "url": "https://security.paloaltonetworks.com/CVE-2020-1999",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "psirt@paloaltonetworks.com"
    },
    {
      "url": "https://security.paloaltonetworks.com/CVE-2020-1999",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "psirt@paloaltonetworks.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability exists in the Palo Alto Network PAN-OS signature-based threat detection engine that allows an attacker to communicate with devices in the network in a way that is not analyzed for threats by sending data through specifically crafted TCP packets. This technique evades signature-based threat detection. This issue impacts: PAN-OS 8.1 versions earlier than 8.1.17; PAN-OS 9.0 versions earlier than 9.0.11; PAN-OS 9.1 versions earlier than 9.1.5; All versions of PAN-OS 7.1 and PAN-OS 8.0."
    },
    {
      "lang": "es",
      "value": "Se presenta una vulnerabilidad en el motor de detección de amenazas basado en firmas de PAN-OS de Palo Alto Network que permite a un atacante comunicarse con dispositivos en la red de una manera que no se analiza en busca de amenazas mediante el envío de datos mediante paquetes TCP específicamente diseñados. Esta técnica evade la detección de amenazas basada en firmas. Este problema afecta a: PAN-OS versiones 8.1 anteriores a 8.1.17; PAN-OS versiones 9.0 anteriores a 9.0.11; PAN-OS versiones 9.1 anteriores a 9.1.5; Todas las versiones de PAN-OS 7.1 y PAN-OS 8.0"
    }
  ],
  "lastModified": "2026-06-17T03:02:48.180",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:paloaltonetworks:pan-os:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "9223062F-C3E8-4D86-88E4-70D775D1151F",
              "versionEndIncluding": "7.1.26",
              "versionStartIncluding": "7.1.0"
            },
            {
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              "vulnerable": true,
              "matchCriteriaId": "2BEFBF38-AF84-4477-A6B9-5BDD51D54F4F",
              "versionEndIncluding": "8.0.20",
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          "operator": "OR"
        }
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  ],
  "sourceIdentifier": "psirt@paloaltonetworks.com"
}