{"id":"UBUNTU-CVE-2026-115349","details":"Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity denial of service vulnerability in the parse_link_text function in src/mistune/helpers.py. Attackers can submit markdown with deeply nested square brackets triggering quadratic parsing time, exhausting server CPU with small crafted requests.","modified":"2026-10-27T04:17:45.418060633Z","published":"2026-10-26T00:00:00Z","upstream":["CVE-2026-115349"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-115349"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-115349"},{"type":"REPORT","url":"https://github.com/lepture/mistune/security/advisories/GHSA-3q64-rw38-243v"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/mistune-3.0.0-before-3.3.0-denial-of-service-via-nested-bracket-parsing"}],"affected":[{"package":{"name":"mistune","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.6-2","0.7.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python-mistune","binary_version":"0.7.1-1"},{"binary_version":"0.7.1-1","binary_name":"python3-mistune"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}},{"package":{"name":"mistune","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.7.4-1","0.8-1","0.8.1-1","0.8.3-2"],"ecosystem_specific":{"binaries":[{"binary_name":"python-mistune","binary_version":"0.8.3-2"},{"binary_name":"python3-mistune","binary_version":"0.8.3-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}},{"package":{"name":"mistune","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.8.4-1","0.8.4-2"],"ecosystem_specific":{"binaries":[{"binary_version":"0.8.4-2","binary_name":"python3-mistune"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}},{"package":{"name":"mistune","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.8.4-4","0.8.4-5","2.0.0-1+really0.8.4-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-mistune","binary_version":"2.0.0-1+really0.8.4-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}},{"package":{"name":"mistune","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.4-2","3.0.2-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-mistune","binary_version":"3.0.2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}},{"package":{"name":"mistune","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.4-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-mistune","binary_version":"3.1.4-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}},{"package":{"name":"mistune","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/mistune?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.3-1","3.1.4-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-mistune","binary_version":"3.1.4-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-115349.json"}}],"schema_version":"1.9.2","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_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}