{"id":"CVE-2026-44897","summary":"Mistune Heading ID Attribute Injection XSS","details":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading() builds the opening \u003chN\u003e tag by string-concatenating the id attribute value directly into the HTML — with no call to escape(), safe_entity(), or any other sanitisation function. A double-quote character \" in the id value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, src=, href=, etc.) into the heading element. This vulnerability is fixed in 3.2.1.","aliases":["GHSA-v87v-83h2-53w7","PYSEC-2026-2207"],"modified":"2026-07-26T03:32:20.104817768Z","published":"2026-05-26T20:40:42.290Z","related":["SUSE-SU-2026:21858-1","openSUSE-SU-2026:10761-1","openSUSE-SU-2026:20827-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44897.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-2026-44897.json"},{"type":"ADVISORY","url":"https://github.com/lepture/mistune/security/advisories/GHSA-v87v-83h2-53w7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44897"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lepture/mistune","events":[{"introduced":"0"},{"fixed":"067f90861088a496942f5eb43236135352b85d39"}],"database_specific":{"cpe":"cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"3.2.1"}],"source":["AFFECTED_FIELD","CPE_RANGE","REFERENCES"]}}],"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-2026-44897.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"}]}