CVE-2021-43535 (GCVE-0-2021-43535)

Vulnerability from cvelistv5 – Published: 2021-12-08 21:20 – Updated: 2024-08-04 03:55
VLAI
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.
Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE
  • Use-after-free in HTTP2 Session object
Assigner
References
Impacted products
Vendor Product Version
Mozilla Firefox Affected: unspecified , < 93 (custom)
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Mozilla Thunderbird Affected: unspecified , < 91.3 (custom)
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Mozilla Firefox ESR Affected: unspecified , < 91.3 (custom)
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Advisory\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2021-50/\",\"source\":\"security@mozilla.org\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://bugzilla.mozilla.org/show_bug.cgi?id=1667102\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Issue Tracking\",\"Permissions Required\",\"Vendor Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"https://www.debian.org/security/2021/dsa-5026\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://www.debian.org/security/2022/dsa-5034\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Issue Tracking\",\"Third Party Advisory\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2021-43/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2021-49/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2021-50/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Vendor Advisory\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2025-11-21T14:53:49+00:00",
      "cve": "CVE-2021-43535",
      "id": "CVE-2021-43535",
      "initial_release_date": "2021-11-02T00:00:00+00:00",
      "product_status:fixed": "144",
      "product_status:known_affected": "4",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "Mozilla: Use-after-free in HTTP2 Session object",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-43535.json",
      "version": "3"
    }
  }
}



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Tags
Taxonomy of the tags.





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

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.