{"id":"UBUNTU-CVE-2026-71478","details":"league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.","modified":"2026-08-13T00:14:08Z","published":"2026-08-06T22:18:00Z","upstream":["CVE-2026-71478"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-71478"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-71478"},{"type":"REPORT","url":"https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c2c4431a8e2c"},{"type":"REPORT","url":"https://github.com/thephpleague/commonmark/releases/tag/2.9.0"},{"type":"REPORT","url":"https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52mc"}],"affected":[{"package":{"name":"markdown","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/markdown?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-7","1.0.1-8"],"ecosystem_specific":{"binaries":[{"binary_name":"markdown","binary_version":"1.0.1-8"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"markdown","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/markdown?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-9","1.0.1-10"],"ecosystem_specific":{"binaries":[{"binary_name":"markdown","binary_version":"1.0.1-10"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"markdown","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/markdown?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-10"],"ecosystem_specific":{"binaries":[{"binary_version":"1.0.1-10","binary_name":"markdown"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"commonmark","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/commonmark?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1-3"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-commonmark","binary_version":"0.9.1-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"markdown","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/markdown?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-10.1"],"ecosystem_specific":{"binaries":[{"binary_name":"markdown","binary_version":"1.0.1-10.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"commonmark","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/commonmark?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1-4","0.9.1-5"],"ecosystem_specific":{"binaries":[{"binary_version":"0.9.1-5","binary_name":"python3-commonmark"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"markdown","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/markdown?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-12"],"ecosystem_specific":{"binaries":[{"binary_version":"1.0.1-12","binary_name":"markdown"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"commonmark","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/commonmark?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1-8","0.9.1-8build1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-commonmark","binary_version":"0.9.1-8build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}},{"package":{"name":"markdown","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/markdown?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-14"],"ecosystem_specific":{"binaries":[{"binary_name":"markdown","binary_version":"1.0.1-14"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71478.json"}}],"schema_version":"1.9.0","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"}]}