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CVE-2021-21323

Estado: ModificadaMedia (5.3)—

Brave is an open source web browser with a focus on privacy and security. In Brave versions 1.17.73-1.20.103, the CNAME adblocking feature added in Brave 1.17.73 accidentally initiated DNS requests that bypassed the Brave Tor proxy. Users with adblocking enabled would leak DNS requests from Tor windows to their DNS provider. (DNS requests that were not initiated by CNAME adblocking would go through Tor as expected.) This is fixed in Brave version 1.20.108

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Brave — Brave

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2021-21323",
  "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": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "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
      },
      {
        "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:L/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "brave",
          "product": "brave-browser",
          "versions": [
            {
              "status": "affected",
              "version": ">= 1.17.73, < 1.20.108"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-02-23T23:15:13.317",
  "references": [
    {
      "url": "https://github.com/brave/brave-browser/issues/13527",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/brave/brave-browser/security/advisories/GHSA-mqjf-9x5g-2rv6",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/brave/brave-core/commit/12fe321eaad8acc1cbd1d70b4128f687777bcf15",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/brave/brave-core/pull/7769",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://hackerone.com/reports/1077022",
      "tags": [
        "Permissions Required",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/brave/brave-browser/issues/13527",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/brave/brave-browser/security/advisories/GHSA-mqjf-9x5g-2rv6",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/brave/brave-core/commit/12fe321eaad8acc1cbd1d70b4128f687777bcf15",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/brave/brave-core/pull/7769",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://hackerone.com/reports/1077022",
      "tags": [
        "Permissions Required",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Brave is an open source web browser with a focus on privacy and security. In Brave versions 1.17.73-1.20.103, the CNAME adblocking feature added in Brave 1.17.73 accidentally initiated DNS requests that bypassed the Brave Tor proxy. Users with adblocking enabled would leak DNS requests from Tor windows to their DNS provider. (DNS requests that were not initiated by CNAME adblocking would go through Tor as expected.) This is fixed in Brave version 1.20.108"
    },
    {
      "lang": "es",
      "value": "Brave es un navegador web de código abierto que se centra en la privacidad y la seguridad.&#xa0;En Brave versiones 1.17.73-1.20.103, la funcionalidad CNAME adblocking agregada en Brave versión 1.17.73, inició accidentalmente peticiones de DNS que omitieron el proxy Brave Tor.&#xa0;Los usuarios con adblocking habilitado filtrarían las peticiones DNS de las ventanas Tor a su proveedor de DNS.&#xa0;(Las peticiones DNS que no fueron iniciadas por el CNAME adblocking pasarían por Tor como se esperaba). Esto se corrigió en Brave versión 1.20.108"
    }
  ],
  "lastModified": "2026-06-17T03:35:17.803",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:brave:brave:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "AD17A757-9D61-4E54-849D-AD603B5001F3",
              "versionEndIncluding": "1.20.103",
              "versionStartIncluding": "1.17.73"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security-advisories@github.com"
}