CVE-2025-66400

mdast-util-to-hast is an mdast utility to transform to hast. From 13.0.0 to before 13.2.1, multiple (unprefixed) classnames could be added in markdown source by using character references. This could make rendered user supplied markdown code elements appear like the rest of the page. This vulnerability is fixed in 13.2.1.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/syntax-tree/mdast-util-to-hast/commit/6fc783ae6abdeb798fd5a68e7f3f21411dde7403	Patch
https://github.com/syntax-tree/mdast-util-to-hast/commit/ab3a79570a1afbfa7efef5d4a0cd9b5caafbc5d7	Patch
https://github.com/syntax-tree/mdast-util-to-hast/security/advisories/GHSA-4fh9-h7wg-q85m	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:unifiedjs:mdast-util-to-hast:*:*:*:*:*:node.js:*:*

History

18 Oct 2026, 18:10

Type	Values Removed	Values Added
Summary		(es) mdast-util-to-hast es una utilidad de mdast para transformar a hast. Desde la 13.0.0 hasta la 13.2.1, múltiples nombres de clase (sin prefijo) podían añadirse en el código fuente de markdown mediante el uso de referencias de caracteres. Esto podría hacer que los elementos de código markdown renderizados y proporcionados por el usuario aparecieran como el resto de la página. Esta vulnerabilidad está corregida en la 13.2.1.

Information

Published : 2025-12-01 23:15

Updated : 2026-10-18 18:10

NVD link : CVE-2025-66400

Mitre link : CVE-2025-66400

CVE.ORG link : CVE-2025-66400

JSON object : View

Products Affected

unifiedjs

mdast-util-to-hast

CWE

CWE-20

Improper Input Validation

CWE-915

Improperly Controlled Modification of Dynamically-Determined Object Attributes

NVD-CWE-Other

{"id": "CVE-2025-66400", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-66400", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2025-12-02T15:34:16.267018Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.9, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/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": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "LOW", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "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": "syntax-tree", "product": "mdast-util-to-hast", "versions": [{"status": "affected", "version": ">= 13.0.0, < 13.2.1"}]}]}], "published": "2025-12-01T23:15:53.070", "references": [{"url": "https://github.com/syntax-tree/mdast-util-to-hast/commit/6fc783ae6abdeb798fd5a68e7f3f21411dde7403", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/syntax-tree/mdast-util-to-hast/commit/ab3a79570a1afbfa7efef5d4a0cd9b5caafbc5d7", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/syntax-tree/mdast-util-to-hast/security/advisories/GHSA-4fh9-h7wg-q85m", "tags": ["Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-915"}]}, {"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-Other"}]}], "descriptions": [{"lang": "en", "value": "mdast-util-to-hast is an mdast utility to transform to hast. From 13.0.0 to before 13.2.1, multiple (unprefixed) classnames could be added in markdown source by using character references. This could make rendered user supplied markdown code elements appear like the rest of the page. This vulnerability is fixed in 13.2.1."}, {"lang": "es", "value": "mdast-util-to-hast es una utilidad de mdast para transformar a hast. Desde la 13.0.0 hasta la 13.2.1, m\u00faltiples nombres de clase (sin prefijo) pod\u00edan a\u00f1adirse en el c\u00f3digo fuente de markdown mediante el uso de referencias de caracteres. Esto podr\u00eda hacer que los elementos de c\u00f3digo markdown renderizados y proporcionados por el usuario aparecieran como el resto de la p\u00e1gina. Esta vulnerabilidad est\u00e1 corregida en la 13.2.1."}], "lastModified": "2026-10-18T18:10:00.100", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:unifiedjs:mdast-util-to-hast:*:*:*:*:*:node.js:*:*", "vulnerable": true, "matchCriteriaId": "2757E694-2D1F-4B57-A544-05363721D945", "versionEndExcluding": "13.2.1", "versionStartIncluding": "13.0.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}