CVE-2026-59926

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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2	Patch
https://github.com/lepture/mistune/releases/tag/v3.2.1	Release Notes
https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*

History

25 Oct 2026, 17:10

Type	Values Removed	Values Added
Summary		(es) Mistune es un analizador de Markdown de Python con renderizadores y complementos. Antes de la versión 3.2.1, render_admonition() en src/mistune/directives/admonition.py concatena la opción :class: de la directiva Admonition en el atributo de clase HTML sin escapar, permitiendo la inyección de atributos y cross-site scripting incluso cuando el modo de escape de HTMLRenderer está habilitado. Este problema se ha solucionado en la versión 3.2.1.

Information

Published : 2026-07-08 17:17

Updated : 2026-10-25 17:10

NVD link : CVE-2026-59926

Mitre link : CVE-2026-59926

CVE.ORG link : CVE-2026-59926

JSON object : View

Products Affected

mistune_project

mistune

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

{"id": "CVE-2026-59926", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-59926", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-08T17:48:29.407727Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 6.1, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 2.7, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 5.3, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "PASSIVE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "LOW", "vulnIntegrityImpact": "LOW", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "LOW", "vulnConfidentialityImpact": "LOW", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "lepture", "product": "mistune", "versions": [{"status": "affected", "version": "< 3.2.1"}]}]}], "published": "2026-07-08T17:17:28.323", "references": [{"url": "https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/lepture/mistune/releases/tag/v3.2.1", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h", "tags": ["Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-79"}]}], "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."}, {"lang": "es", "value": "Mistune es un analizador de Markdown de Python con renderizadores y complementos. Antes de la versi\u00f3n 3.2.1, render_admonition() en src/mistune/directives/admonition.py concatena la opci\u00f3n :class: de la directiva Admonition en el atributo de clase HTML sin escapar, permitiendo la inyecci\u00f3n de atributos y cross-site scripting incluso cuando el modo de escape de HTMLRenderer est\u00e1 habilitado. Este problema se ha solucionado en la versi\u00f3n 3.2.1."}], "lastModified": "2026-10-25T17:10:00.197", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "63E1B933-D2E2-44EF-A56C-94483300845B", "versionEndExcluding": "3.3.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}