{"id":"CVE-2026-59926","state":"PUBLISHED","title":"Mistune: XSS via unescaped class option in Admonition directive","description":"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.","publishedAt":"2026-07-08T16:16:15.681Z","updatedAt":"2026-07-08T19:40:52.229Z","severity":{"score":5.3,"label":"Medium","version":"4.0","vector":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["lepture mistune"],"affected":[{"vendor":"lepture","product":"mistune","versions":[{"version":"< 3.2.1","status":"affected"}]}],"references":["https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h","https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2","https://github.com/lepture/mistune/releases/tag/v3.2.1"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59926.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59926","state":"PUBLISHED","datePublished":"2026-07-08T16:16:15.681Z","dateUpdated":"2026-07-08T19:40:52.229Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-07T18:20:06.126Z"},"containers":{"cna":{"title":"Mistune: XSS via unescaped class option in Admonition directive","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"lepture","product":"mistune","versions":[{"version":"< 3.2.1","status":"affected"}]}],"references":[{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h","name":"https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2","name":"https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2","tags":["x_refsource_MISC"]},{"url":"https://github.com/lepture/mistune/releases/tag/v3.2.1","name":"https://github.com/lepture/mistune/releases/tag/v3.2.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-08T16:16:15.681Z"},"source":{"advisory":"GHSA-g97x-gvcm-x72h","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-08T17:48:29.407727Z","id":"CVE-2026-59926","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-08T19:40:52.229Z"}}]}}}