{"id":"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.","aliases":["GHSA-g97x-gvcm-x72h","PYSEC-2026-2214"],"modified":"2026-07-17T18:29:35.777428930Z","published":"2026-07-08T16:16:15.681Z","related":["SUSE-SU-2026:22655-1","openSUSE-SU-2026:21339-1"],"database_specific":{"cwe_ids":["CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59926.json","cna_assigner":"GitHub_M"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lepture/mistune","events":[{"introduced":"0"},{"fixed":"15c3b79325125272263d7d42492ec8f757447191"},{"fixed":"a3cb6e5655308797e8be021d6c7b5bab13cbace2"},{"fixed":"067f90861088a496942f5eb43236135352b85d39"}],"database_specific":{"cpe":"cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"3.3.0"}],"source":["CPE_RANGE","REFERENCES"]}}],"versions":["v3.2.1","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-2026-59926.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N"}]}