{"id":"USN-8077-1","summary":"python-bleach vulnerabilities","details":"It was discovered that Bleach did not properly sanitize URI attributes\ncontaining character entities. An attacker could possibly use this issue\nto construct a URI with a disallowed scheme that would bypass\nsanitization, leading to cross-site scripting. This issue only affected\nUbuntu 18.04 LTS. (CVE-2018-7753)\n\nYaniv Nizry discovered that Bleach was vulnerable to a mutation\ncross-site scripting issue when sanitizing HTML with the noscript tag\nand a raw tag in the allowed tags list. An attacker could possibly\nuse this issue to inject malicious content, leading to cross-site\nscripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2020-6802)\n\nYaniv Nizry discovered that Bleach was vulnerable to a mutation\ncross-site scripting issue when sanitizing HTML with RCDATA together\nwith svg or math tags in the allowed tags list. An attacker could\npossibly use this issue to inject malicious content, leading to\ncross-site scripting. (CVE-2020-6816)\n\nIt was discovered that Bleach incorrectly handled parsing of style\nattributes when sanitizing HTML. An attacker could possibly use this\nissue to perform a regular expression denial of service, leading to\nexcessive resource consumption. (CVE-2020-6817)\n\nYaniv Nizry and Michał Bentkowski discovered that Bleach was vulnerable\nto a mutation cross-site scripting issue when sanitizing HTML with\ncertain combinations of allowed tags. An attacker could possibly use\nthis issue to inject malicious content, leading to cross-site scripting.\n(CVE-2021-23980)","modified":"2026-06-25T13:32:31.684046454Z","published":"2026-03-05T16:04:13Z","related":["UBUNTU-CVE-2018-7753","UBUNTU-CVE-2020-6802","UBUNTU-CVE-2020-6816","UBUNTU-CVE-2020-6817","UBUNTU-CVE-2021-23980"],"upstream":["UBUNTU-CVE-2018-7753","UBUNTU-CVE-2020-6802","UBUNTU-CVE-2020-6816","UBUNTU-CVE-2020-6817","UBUNTU-CVE-2021-23980"],"references":[{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8077-1"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2018-7753"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-6802"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-6816"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-6817"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-23980"}],"affected":[{"package":{"name":"python-bleach","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/python-bleach?arch=source&distro=esm-apps%2Fxenial"},"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_version":"1.4.2-1ubuntu0.1~esm1","binary_name":"python-bleach"},{"binary_name":"python3-bleach","binary_version":"1.4.2-1ubuntu0.1~esm1"}]},"database_specific":{"cves_map":{"cves":[{"id":"CVE-2020-6816","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]},{"id":"CVE-2020-6817","severity":[{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","type":"CVSS_V3"},{"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"}]},{"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2021-23980"}],"ecosystem":"Ubuntu:Pro:16.04:LTS"},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8077-1.json"}},{"package":{"name":"python-bleach","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/python-bleach?arch=source&distro=esm-apps%2Fbionic"},"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":{"cves_map":{"ecosystem":"Ubuntu:Pro:18.04:LTS","cves":[{"id":"CVE-2018-7753","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]},{"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}],"id":"CVE-2020-6802"},{"id":"CVE-2020-6816","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]},{"id":"CVE-2020-6817","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"}]},{"id":"CVE-2021-23980","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"score":"medium","type":"Ubuntu"}]}]},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8077-1.json"}},{"package":{"name":"python-bleach","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/python-bleach?arch=source&distro=esm-apps%2Ffocal"},"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":{"binaries":[{"binary_name":"python3-bleach","binary_version":"3.1.1-1ubuntu0.1~esm1"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"cves_map":{"ecosystem":"Ubuntu:Pro:20.04:LTS","cves":[{"id":"CVE-2020-6816","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]},{"severity":[{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","type":"CVSS_V3"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2020-6817"},{"id":"CVE-2021-23980","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}]},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8077-1.json"}}],"schema_version":"1.7.5"}