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CVE-2021-21706

Status: ModifiedMedium (6.5)—

In PHP versions 7.3.x below 7.3.31, 7.4.x below 7.4.24 and 8.0.x below 8.0.11, in Microsoft Windows environment, ZipArchive::extractTo may be tricked into writing a file outside target directory when extracting a ZIP file, thus potentially causing files to be created or overwritten, subject to OS permissions.

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)

PHP — PHP

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-21706",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 4.3,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security@php.net",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.6
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 6.5,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security@php.net",
      "affectedData": [
        {
          "vendor": "PHP Group",
          "product": "PHP",
          "versions": [
            {
              "status": "affected",
              "version": "7.3.x",
              "lessThan": "7.3.31",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "version": "7.4.x",
              "lessThan": "7.4.24",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "version": "8.0.X",
              "lessThan": "8.0.11",
              "versionType": "custom"
            }
          ],
          "platforms": [
            "Windows"
          ]
        }
      ]
    }
  ],
  "published": "2021-10-04T04:15:08.350",
  "references": [
    {
      "url": "https://bugs.php.net/bug.php?id=81420",
      "tags": [
        "Issue Tracking",
        "Patch",
        "Vendor Advisory"
      ],
      "source": "security@php.net"
    },
    {
      "url": "https://security.netapp.com/advisory/ntap-20211029-0007/",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security@php.net"
    },
    {
      "url": "https://bugs.php.net/bug.php?id=81420",
      "tags": [
        "Issue Tracking",
        "Patch",
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://security.netapp.com/advisory/ntap-20211029-0007/",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security@php.net",
      "description": [
        {
          "lang": "en",
          "value": "CWE-24"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In PHP versions 7.3.x below 7.3.31, 7.4.x below 7.4.24 and 8.0.x below 8.0.11, in Microsoft Windows environment, ZipArchive::extractTo may be tricked into writing a file outside target directory when extracting a ZIP file, thus potentially causing files to be created or overwritten, subject to OS permissions."
    },
    {
      "lang": "es",
      "value": "En PHP versiones de 7.3.x por debajo de 7.3.31, versiones 7.4.x por debajo de 7.4.24 y 8.0.x por debajo de 8.0.11, en el entorno de Microsoft Windows, la función ZipArchive::extractTo puede ser engañada para escribir un archivo fuera del directorio de destino cuando es extraído un archivo ZIP, causando así potencialmente una creación o sobreescritura de archivos, sujeto a los permisos del Sistema Operativo"
    }
  ],
  "lastModified": "2026-06-17T03:36:02.040",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:php:php:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "FB0C3B54-5557-4013-9453-CCAB94BF6A34",
              "versionEndExcluding": "7.3.31",
              "versionStartIncluding": "7.3.0"
            },
            {
              "criteria": "cpe:2.3:a:php:php:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "C714AE0D-1990-455D-BEA7-B3FF454DFEBF",
              "versionEndExcluding": "7.4.24",
              "versionStartIncluding": "7.4.0"
            },
            {
              "criteria": "cpe:2.3:a:php:php:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "35A8B10D-C9FF-474F-BEC1-196F6DDC4948",
              "versionEndExcluding": "8.0.11",
              "versionStartIncluding": "8.0.0"
            }
          ],
          "operator": "OR"
        },
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*",
              "vulnerable": false,
              "matchCriteriaId": "A2572D17-1DE6-457B-99CC-64AFD54487EA"
            }
          ],
          "operator": "OR"
        }
      ],
      "operator": "AND"
    }
  ],
  "sourceIdentifier": "security@php.net"
}