{"id":"UBUNTU-CVE-2021-43818","details":"lxml is a library for processing XML and HTML in the Python language. Prior to version 4.6.5, the HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should upgrade to lxml 4.6.5 to receive a patch. There are no known workarounds available.","modified":"2026-02-02T07:30:09.503396Z","published":"2021-12-13T18:15:00Z","related":["USN-5225-1"],"upstream":["CVE-2021-43818"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-43818"},{"type":"REPORT","url":"https://github.com/lxml/lxml/security/advisories/GHSA-55x5-fj6c-h6m8"},{"type":"REPORT","url":"https://github.com/lxml/lxml/commit/12fa9669007180a7bb87d990c375cf91ca5b664a"},{"type":"REPORT","url":"https://github.com/lxml/lxml/commit/f2330237440df7e8f39c3ad1b1aa8852be3b27c0"},{"type":"REPORT","url":"https://github.com/lxml/lxml/commit/f2330237440df7e8f39c3ad1b1aa8852be3b27c0"},{"type":"REPORT","url":"https://github.com/lxml/lxml/commit/a3eacbc0dcf1de1c822ec29fb7d090a4b1712a9c#diff-59130575b4fb2932c957db2922977d7d89afb0b2085357db1a14615a2fcad776"},{"type":"REPORT","url":"https://github.com/lxml/lxml/commit/12fa9669007180a7bb87d990c375cf91ca5b664a"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5225-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-43818"}],"affected":[{"package":{"name":"lxml","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/lxml@3.3.3-1ubuntu0.2+esm5?arch=source&distro=trusty/esm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.3.3-1ubuntu0.2+esm5"}]}],"versions":["3.2.0-1","3.3.0~beta2-1","3.3.0~beta4-1","3.3.1-1","3.3.2-1","3.3.2-1build1","3.3.3-1","3.3.3-1ubuntu0.1","3.3.3-1ubuntu0.2","3.3.3-1ubuntu0.2+esm1","3.3.3-1ubuntu0.2+esm2","3.3.3-1ubuntu0.2+esm3"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"python-lxml","binary_version":"3.3.3-1ubuntu0.2+esm5"},{"binary_name":"python3-lxml","binary_version":"3.3.3-1ubuntu0.2+esm5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43818.json"}},{"package":{"name":"lxml","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/lxml@3.5.0-1ubuntu0.4+esm2?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.5.0-1ubuntu0.4+esm2"}]}],"versions":["3.4.4-1","3.5.0-1","3.5.0-1build1","3.5.0-1ubuntu0.1","3.5.0-1ubuntu0.2","3.5.0-1ubuntu0.3","3.5.0-1ubuntu0.4"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"python-lxml","binary_version":"3.5.0-1ubuntu0.4+esm2"},{"binary_version":"3.5.0-1ubuntu0.4+esm2","binary_name":"python3-lxml"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43818.json"}},{"package":{"name":"lxml","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/lxml@4.2.1-1ubuntu0.6?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.2.1-1ubuntu0.6"}]}],"versions":["4.0.0-1","4.1.0-1","4.2.0-1","4.2.1-1","4.2.1-1ubuntu0.1","4.2.1-1ubuntu0.2","4.2.1-1ubuntu0.3","4.2.1-1ubuntu0.4"],"ecosystem_specific":{"binaries":[{"binary_name":"python-lxml","binary_version":"4.2.1-1ubuntu0.6"},{"binary_name":"python3-lxml","binary_version":"4.2.1-1ubuntu0.6"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43818.json"}},{"package":{"name":"lxml","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/lxml@4.5.0-1ubuntu0.5?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.0-1ubuntu0.5"}]}],"versions":["4.4.1-1","4.4.1-1build1","4.4.2-1","4.5.0-1","4.5.0-1ubuntu0.1","4.5.0-1ubuntu0.2","4.5.0-1ubuntu0.3"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"4.5.0-1ubuntu0.5","binary_name":"python-lxml"},{"binary_name":"python3-lxml","binary_version":"4.5.0-1ubuntu0.5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43818.json"}},{"package":{"name":"lxml","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/lxml@4.7.1-1?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.7.1-1"}]}],"versions":["4.6.3+dfsg-0.1","4.6.4-1","4.6.4-1ubuntu1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"python3-lxml","binary_version":"4.7.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-43818.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}