{"id":"CVE-2026-44898","summary":"Mistune TOC Anchor Injection XSS","details":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a \u003cul\u003e table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href=\"#\u003cid\u003e\") and the text value (used as the visible link label) are inserted into \u003ca\u003e tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from user-supplied heading text (the standard use-case for readable slug anchors), an attacker can craft a heading whose text breaks out of the href=\"#...\" attribute context, injecting arbitrary HTML tags including \u003cscript\u003e blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.","aliases":["GHSA-6269-cqxg-mhhv","PYSEC-2026-2208"],"modified":"2026-08-12T03:30:10.799548872Z","published":"2026-05-26T20:41:53.805Z","related":["SUSE-SU-2026:21858-1","SUSE-SU-2026:2949-1","openSUSE-SU-2026:20827-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44898.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-79"]},"references":[{"type":"WEB","url":"https://github.com/lepture/mistune/releases/tag/v3.2.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44898.json"},{"type":"ADVISORY","url":"https://github.com/lepture/mistune/security/advisories/GHSA-6269-cqxg-mhhv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44898"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lepture/mistune","events":[{"introduced":"0"},{"fixed":"067f90861088a496942f5eb43236135352b85d39"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"3.2.1"}],"source":["AFFECTED_FIELD","CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*"}}],"versions":["v3.2.0","v3.1.4","v3.1.3","v3.1.2","v3.1.1","v3.1.0","v3.0.1","v3.0.0","v3.0.0rc5","v3.0.0rc4","v3.0.0rc3","v3.0.0rc2","v3.0.0rc1","v3.0.0a3","v3.0.0a2","v3.0.0a1","v2.0.2","v2.0.1","v2.0.0","v2.0.0rc1","v2.0.0a6","v2.0.0a5","v2.0.0a4","v2.0.0a3","v2.0.0a2","v2.0.0a1","v0.8.4","v0.8.3","v0.8.2","v0.8.1","v0.8","v0.7.4","v0.7.3","v0.7.2","v0.7.1","v0.7","v0.6","v0.5.1","v0.5","v0.4.1","v0.4","v0.3.1","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-44898.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"}]}