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CVE-2021-29983

Status: ModifiedMedium (6.5)—

Firefox for Android could get stuck in fullscreen mode and not exit it even after normal interactions that should cause it to exit. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91.

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-2021-29983",
  "cveTags": [],
  "metrics": {
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      {
        "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": [
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        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
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          "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
      }
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  },
  "affected": [
    {
      "source": "security@mozilla.org",
      "affectedData": [
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          "vendor": "Mozilla",
          "product": "Firefox",
          "versions": [
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              "versionType": "custom"
            }
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  ],
  "published": "2021-08-17T20:15:07.810",
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        "Permissions Required",
        "Vendor Advisory"
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    },
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    },
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      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1719088",
      "tags": [
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        "Permissions Required",
        "Vendor Advisory"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
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      "tags": [
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      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
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  ],
  "vulnStatus": "Modified",
  "weaknesses": [
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
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          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Firefox for Android could get stuck in fullscreen mode and not exit it even after normal interactions that should cause it to exit. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91."
    },
    {
      "lang": "es",
      "value": "Firefox para Android podía quedarse atascado en el modo de pantalla completa y no salir de él incluso después de las interacciones normales que deberían causar su salida. *Nota: Este problema sólo afectaba a Firefox para Android. Otros sistemas operativos no están afectados*. Esta vulnerabilidad afecta a Firefox versiones anteriores a 91."
    }
  ],
  "lastModified": "2026-06-17T03:48:33.307",
  "configurations": [
    {
      "nodes": [
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          "cpeMatch": [
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              "matchCriteriaId": "E2960D13-5DCE-4A97-8586-B259C31DEBFE",
              "versionEndExcluding": "91.0"
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}