ubuntu-cve-2021-43535
Vulnerability from osv_ubuntu
Published
2021-12-08 22:15
Modified
2026-04-22 07:40
Summary
Details

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
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "thunderbird",
            "binary_version": "1:91.5.0+build1-0ubuntu0.18.04.1"
          },
          {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:91.5.0+build1-0ubuntu0.18.04.1"
          },
          {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:91.5.0+build1-0ubuntu0.18.04.1"
          },
          {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:91.5.0+build1-0ubuntu0.18.04.1"
          },
          {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:91.5.0+build1-0ubuntu0.18.04.1"
          },
          {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:91.5.0+build1-0ubuntu0.18.04.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "thunderbird",
        "purl": "pkg:deb/ubuntu/thunderbird@1:91.5.0+build1-0ubuntu0.18.04.1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:91.5.0+build1-0ubuntu0.18.04.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:52.4.0+build1-0ubuntu2",
        "1:52.6.0+build1-0ubuntu1",
        "1:52.7.0+build1-0ubuntu1",
        "1:52.8.0+build1-0ubuntu0.18.04.1",
        "1:52.9.1+build3-0ubuntu0.18.04.1",
        "1:60.2.1+build1-0ubuntu0.18.04.2",
        "1:60.4.0+build2-0ubuntu0.18.04.1",
        "1:60.5.1+build2-0ubuntu0.18.04.1",
        "1:60.6.1+build2-0ubuntu0.18.04.1",
        "1:60.7.0+build1-0ubuntu0.18.04.1",
        "1:60.7.1+build1-0ubuntu0.18.04.1",
        "1:60.7.2+build2-0ubuntu0.18.04.1",
        "1:60.8.0+build1-0ubuntu0.18.04.1",
        "1:60.9.0+build1-0ubuntu0.18.04.1",
        "1:68.2.1+build1-0ubuntu0.18.04.1",
        "1:68.2.2+build1-0ubuntu0.18.04.1",
        "1:68.4.1+build1-0ubuntu0.18.04.1",
        "1:68.7.0+build1-0ubuntu0.18.04.1",
        "1:68.8.0+build2-0ubuntu0.18.04.2",
        "1:68.10.0+build1-0ubuntu0.18.04.1",
        "1:78.8.1+build1-0ubuntu0.18.04.1",
        "1:78.11.0+build1-0ubuntu0.18.04.2",
        "1:78.13.0+build1-0ubuntu0.18.04.1",
        "1:78.14.0+build1-0ubuntu0.18.04.1",
        "1:78.14.0+build1-0ubuntu0.18.04.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "thunderbird",
            "binary_version": "1:91.5.0+build1-0ubuntu0.20.04.1"
          },
          {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:91.5.0+build1-0ubuntu0.20.04.1"
          },
          {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:91.5.0+build1-0ubuntu0.20.04.1"
          },
          {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:91.5.0+build1-0ubuntu0.20.04.1"
          },
          {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:91.5.0+build1-0ubuntu0.20.04.1"
          },
          {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:91.5.0+build1-0ubuntu0.20.04.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "thunderbird",
        "purl": "pkg:deb/ubuntu/thunderbird@1:91.5.0+build1-0ubuntu0.20.04.1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:91.5.0+build1-0ubuntu0.20.04.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:68.1.2+build1-0ubuntu1",
        "1:68.1.2+build1-0ubuntu2",
        "1:68.2.1+build1-0ubuntu1",
        "1:68.2.2+build1-0ubuntu1",
        "1:68.3.0+build2-0ubuntu1",
        "1:68.3.1+build1-0ubuntu2",
        "1:68.4.1+build1-0ubuntu1",
        "1:68.4.2+build2-0ubuntu1",
        "1:68.5.0+build1-0ubuntu1",
        "1:68.6.0+build2-0ubuntu1",
        "1:68.7.0+build1-0ubuntu1",
        "1:68.7.0+build1-0ubuntu2",
        "1:68.8.0+build2-0ubuntu0.20.04.2",
        "1:68.10.0+build1-0ubuntu0.20.04.1",
        "1:78.7.1+build1-0ubuntu0.20.04.1",
        "1:78.8.1+build1-0ubuntu0.20.04.1",
        "1:78.11.0+build1-0ubuntu0.20.04.2",
        "1:78.13.0+build1-0ubuntu0.20.04.2",
        "1:78.14.0+build1-0ubuntu0.20.04.1",
        "1:78.14.0+build1-0ubuntu0.20.04.2"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2021-43535",
  "modified": "2026-04-22T07:40:11Z",
  "published": "2021-12-08T22:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-43535"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-50/"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-43/"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-49/"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1667102"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-5248-1"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2021-43535"
    }
  ],
  "related": [
    "USN-5248-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-43535"
  ]
}



Log in or create an account to share your comment.




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.