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CVE-2021-1861

Status: ModifiedMedium (4.3)—

An issue existed in determining cache occupancy. The issue was addressed through improved logic. This issue is fixed in macOS Big Sur 11.3. A malicious website may be able to track users by setting state in a cache.

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)

Apple — Macos

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-1861",
  "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:P/I:N/A:N",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "product-security@apple.com",
      "affectedData": [
        {
          "vendor": "Apple",
          "product": "macOS",
          "versions": [
            {
              "status": "affected",
              "version": "unspecified",
              "lessThan": "11.3",
              "versionType": "custom"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-09-08T15:15:11.663",
  "references": [
    {
      "url": "https://support.apple.com/en-us/HT212325",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "product-security@apple.com"
    },
    {
      "url": "https://support.apple.com/en-us/HT212325",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue existed in determining cache occupancy. The issue was addressed through improved logic. This issue is fixed in macOS Big Sur 11.3. A malicious website may be able to track users by setting state in a cache."
    },
    {
      "lang": "es",
      "value": "Se presentaba un problema en la determinación de la ocupación de la caché. Se abordó el problema con una lógica mejorada. Este problema se corrigió en macOS Big Sur versión 11.3. Un sitio web malicioso puede ser capaz de rastrear a los usuarios al establecer el estado en una caché"
    }
  ],
  "lastModified": "2026-06-17T03:32:40.950",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "4E699CCC-31F5-458E-A59C-79B3AF143747",
              "versionEndExcluding": "11.3",
              "versionStartIncluding": "11.0"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "product-security@apple.com"
}