{"id":"UBUNTU-CVE-2026-118694","details":"python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated '[a](' or '![a](' sequences, causing _find_balanced to rescan the remaining document for each link and consume quadratic CPU time.","modified":"2026-10-29T20:04:30.936927908Z","published":"2026-10-29T00:00:00Z","upstream":["CVE-2026-118694"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-118694"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-118694"},{"type":"REPORT","url":"https://github.com/trentm/python-markdown2"},{"type":"REPORT","url":"https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L1478-L1492"},{"type":"REPORT","url":"https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L3029"},{"type":"REPORT","url":"https://github.com/trentm/python-markdown2/issues/750"},{"type":"REPORT","url":"https://github.com/trentm/python-markdown2/pull/751"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/python-markdown2-through-2.5.5-denial-of-service-via-unclosed-inline-link-destinations"}],"affected":[{"package":{"name":"python-markdown2","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/python-markdown2?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.7-2"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-markdown2","binary_version":"2.3.7-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-118694.json"}},{"package":{"name":"python-markdown2","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/python-markdown2?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.10-1.1","2.4.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-markdown2","binary_version":"2.4.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-118694.json"}},{"package":{"name":"python-markdown2","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/python-markdown2?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.4.1-1","2.4.11-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-markdown2","binary_version":"2.4.11-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-118694.json"}},{"package":{"name":"python-markdown2","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/python-markdown2?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.4-3"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-markdown2","binary_version":"2.5.4-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-118694.json"}},{"package":{"name":"python-markdown2","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/python-markdown2?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.4.11-1","2.5.4-2","2.5.4-3"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-markdown2","binary_version":"2.5.4-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-118694.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"}]}