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CVE-2018-4221

Status: ModifiedHigh (7.5)—

An issue was discovered in certain Apple products. iOS before 11.4 is affected. macOS before 10.13.5 is affected. The issue involves the "Security" component. It allows web sites to track users by leveraging the transmission of S/MIME client certificates.

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 (2)

Apple — Iphone OSApple — MAC OS X

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2018-4221",
  "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:P/I:N/A:N",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV30": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.0",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "product-security@apple.com",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2018-06-08T18:29:01.447",
  "references": [
    {
      "url": "http://www.securityfocus.com/bid/104897",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "product-security@apple.com"
    },
    {
      "url": "http://www.securitytracker.com/id/1041027",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "product-security@apple.com"
    },
    {
      "url": "https://support.apple.com/HT208848",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "product-security@apple.com"
    },
    {
      "url": "https://support.apple.com/HT208849",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "product-security@apple.com"
    },
    {
      "url": "http://www.securityfocus.com/bid/104897",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.securitytracker.com/id/1041027",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://support.apple.com/HT208848",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://support.apple.com/HT208849",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in certain Apple products. iOS before 11.4 is affected. macOS before 10.13.5 is affected. The issue involves the \"Security\" component. It allows web sites to track users by leveraging the transmission of S/MIME client certificates."
    },
    {
      "lang": "es",
      "value": "Se ha descubierto un problema en ciertos productos Apple. Se han visto afectadas las versiones de iOS anteriores a la 11.4 y las versiones de macOS anteriores a la 10.13.5. El problema implica el componente \"Security\". Permite que los sitios web rastreen usuarios aprovechando la transmisión de certificados de cliente S/MIME."
    }
  ],
  "lastModified": "2026-06-17T01:58:36.817",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "618A2297-91F6-4533-B345-1620635CDA93",
              "versionEndExcluding": "11.4"
            },
            {
              "criteria": "cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "B0B9799C-6891-4D51-9E17-92D1407740F9",
              "versionEndExcluding": "10.13.5"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "product-security@apple.com"
}