{"id":"CVE-2026-59926","aliases":["GHSA-g97x-gvcm-x72h","PYSEC-2026-2214"],"url":"https://o3.security/vulnerability/CVE-2026-59926","summary":"Mistune: XSS via unescaped class option in Admonition directive","details":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.","published":"2026-07-08T16:16:15.681Z","modified":"2026-08-12T03:51:46.633855088Z","cvss":null,"epss":{"score":0.00327,"percentile":0.25382,"asOf":"2026-09-06"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"mistune","fixedVersion":"3.3.0"}],"fix":{"url":"https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2","label":"lepture/mistune@a3cb6e5"},"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/2026/59xxx/CVE-2026-59926.json"},{"type":"ADVISORY","url":"https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59926"},{"type":"FIX","url":"https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:46.633855088Z"}}