FKIE_CVE-2021-43535

Vulnerability from fkie_nvd - Published: 2021-12-08 22:15 - Updated: 2026-06-17 04:11
Severity
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
A use-after-free could have occured when an HTTP2 session object was released on a different thread, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 93, Thunderbird < 91.3, and Firefox ESR < 91.3.
References
security@mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1667102Issue Tracking, Permissions Required, Vendor Advisory
security@mozilla.orghttps://lists.debian.org/debian-lts-announce/2021/12/msg00030.htmlMailing List, Third Party Advisory
security@mozilla.orghttps://lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing List, Third Party Advisory
security@mozilla.orghttps://www.debian.org/security/2021/dsa-5026Third Party Advisory
security@mozilla.orghttps://www.debian.org/security/2022/dsa-5034Issue Tracking, Third Party Advisory
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-43/Vendor Advisory
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-49/Vendor Advisory
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-50/Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://bugzilla.mozilla.org/show_bug.cgi?id=1667102Issue Tracking, Permissions Required, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2021/12/msg00030.htmlMailing List, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing List, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.debian.org/security/2021/dsa-5026Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.debian.org/security/2022/dsa-5034Issue Tracking, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.mozilla.org/security/advisories/mfsa2021-43/Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.mozilla.org/security/advisories/mfsa2021-49/Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.mozilla.org/security/advisories/mfsa2021-50/Vendor Advisory
Impacted products
Vendor Product Version
mozilla firefox *
mozilla firefox_esr *
mozilla thunderbird *
debian debian_linux 9.0
debian debian_linux 10.0
debian debian_linux 11.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Firefox",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "93",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "91.3",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "Firefox ESR",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "91.3",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "security@mozilla.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "B38B28B1-FAB5-47DB-9C73-0CFB79CCDE79",
              "versionEndExcluding": "93.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "DEA65EE6-233C-4CC1-83E8-316748943DAF",
              "versionEndExcluding": "91.3.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "65E19CA9-5FDF-4253-8D56-FD82239F7D93",
              "versionEndExcluding": "91.3.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "07B237A9-69A3-4A9C-9DA0-4E06BD37AE73",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A use-after-free could have occured when an HTTP2 session object was released on a different thread, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox \u003c 93, Thunderbird \u003c 91.3, and Firefox ESR \u003c 91.3."
    },
    {
      "lang": "es",
      "value": "Podr\u00eda haberse producido un uso de memoria previamente liberada cuando un objeto de sesi\u00f3n HTTP2 se liberaba en un hilo diferente, conllevando a una corrupci\u00f3n de memoria y un fallo potencialmente explotable. Esta vulnerabilidad afecta a Firefox versiones anteriores a 93, Thunderbird versiones anteriores a 91.3 y Firefox ESR versiones anteriores a 91.3"
    }
  ],
  "id": "CVE-2021-43535",
  "lastModified": "2026-06-17T04:11:05.183",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 6.8,
          "confidentialityImpact": "PARTIAL",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 6.4,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-12-08T22:15:09.517",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Issue Tracking",
        "Permissions Required",
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      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1667102"
    },
    {
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      "tags": [
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    },
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    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
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      "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
    },
    {
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    },
    {
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    },
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      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-50/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

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