{"id":"UBUNTU-CVE-2021-43535","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.","modified":"2026-04-22T14:59:44.979534Z","published":"2021-12-08T22:15:00Z","related":["USN-5248-1"],"upstream":["CVE-2021-43535"],"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"}],"affected":[{"package":{"name":"thunderbird","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/thunderbird@1:91.5.0+build1-0ubuntu0.18.04.1?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:91.5.0+build1-0ubuntu0.18.04.1"}]}],"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+build1-0ubuntu0.18.04.1"},{"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"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43535.json"}},{"package":{"name":"thunderbird","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/thunderbird@1:91.5.0+build1-0ubuntu0.20.04.1?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:91.5.0+build1-0ubuntu0.20.04.1"}]}],"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"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"thunderbird","binary_version":"1:91.5.0+build1-0ubuntu0.20.04.1"},{"binary_version":"1:91.5.0+build1-0ubuntu0.20.04.1","binary_name":"thunderbird-gnome-support"},{"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"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43535.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}