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CVE-2020-12391

Status: ModifiedHigh (7.5)—

Documents formed using data: URLs in an OBJECT element failed to inherit the CSP of the creating context. This allowed the execution of scripts that should have been blocked, albeit with a unique opaque origin. This vulnerability affects Firefox < 76.

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)

Mozilla — Firefox

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2020-12391",
  "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": [
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        "cvssData": {
          "scope": "UNCHANGED",
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          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "security@mozilla.org",
      "affectedData": [
        {
          "vendor": "Mozilla",
          "product": "Firefox",
          "versions": [
            {
              "status": "affected",
              "version": "unspecified",
              "lessThan": "76",
              "versionType": "custom"
            }
          ]
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      ]
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  ],
  "published": "2020-05-26T18:15:11.293",
  "references": [
    {
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1457100",
      "tags": [
        "Permissions Required"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2020-16/",
      "tags": [
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      "source": "security@mozilla.org"
    },
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      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1457100",
      "tags": [
        "Permissions Required"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
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      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-863"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Documents formed using data: URLs in an OBJECT element failed to inherit the CSP of the creating context. This allowed the execution of scripts that should have been blocked, albeit with a unique opaque origin. This vulnerability affects Firefox < 76."
    },
    {
      "lang": "es",
      "value": "Documentos formados usando datos: las URL en un elemento OBJECT presentaron un fallo al heredar el CSP del contexto de creación. Esto permitió la ejecución de scripts que debieron haber sido bloqueados, aunque con un origen opaco único. Esta vulnerabilidad afecta a Firefox versiones anteriores a 76."
    }
  ],
  "lastModified": "2026-06-17T02:51:44.760",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "versionEndExcluding": "76.0"
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  ],
  "sourceIdentifier": "security@mozilla.org"
}