{"id":"UBUNTU-CVE-2020-6817","details":"bleach.clean behavior parsing style attributes could result in a regular expression denial of service (ReDoS). Calls to bleach.clean with an allowed tag with an allowed style attribute are vulnerable to ReDoS. For example, bleach.clean(..., attributes={'a': ['style']}).","modified":"2026-03-09T11:19:21.037504Z","published":"2023-02-16T22:15:00Z","related":["USN-8077-1"],"upstream":["CVE-2020-6817"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-6817"},{"type":"REPORT","url":"https://github.com/mozilla/bleach/security/advisories/GHSA-vqhp-cxgc-6wmm"},{"type":"REPORT","url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1623633"},{"type":"REPORT","url":"https://github.com/mozilla/bleach/commit/d6018f2539d271963c3e7f54f36ef11900363c69"},{"type":"REPORT","url":"https://github.com/mozilla/bleach/commit/6e74a5027b57055cdaeb040343d32934121392a7"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-6817"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8077-1"}],"affected":[{"package":{"name":"python-bleach","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/python-bleach@1.4.2-1ubuntu0.1~esm1?arch=source&distro=esm-apps/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.4.2-1ubuntu0.1~esm1"}]}],"versions":["1.4-1","1.4.2-1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_name":"python-bleach","binary_version":"1.4.2-1ubuntu0.1~esm1"},{"binary_name":"python3-bleach","binary_version":"1.4.2-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-6817.json"}},{"package":{"name":"python-bleach","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/python-bleach@2.1.2-1ubuntu0.1~esm1?arch=source&distro=esm-apps/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.2-1ubuntu0.1~esm1"}]}],"versions":["2.0-1","2.1.2-1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_name":"python-bleach","binary_version":"2.1.2-1ubuntu0.1~esm1"},{"binary_name":"python3-bleach","binary_version":"2.1.2-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-6817.json"}},{"package":{"name":"python-bleach","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/python-bleach@3.1.1-1ubuntu0.1~esm1?arch=source&distro=esm-apps/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.1-1ubuntu0.1~esm1"}]}],"versions":["3.1.0-1","3.1.0-2","3.1.1-1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_name":"python3-bleach","binary_version":"3.1.1-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-6817.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}