{"id":"EUVD-2025-200113","revision":null,"records":[{"revision":"390aae7acdf04a95b85594b53e02f04f","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-66400","aliases":[],"title":"mdast-util-to-hast unsanitized class attribute","description":"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. 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Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2025-66400","identifiers":["CVE-2025-66400"]},"retained":false,"historicalAffected":[]},{"revision":"7531a214efe84b6b85ff8864e58d8cb1","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-4fh9-h7wg-q85m","aliases":["CVE-2025-66400"],"title":"mdast-util-to-hast has unsanitized class attribute","description":"### Impact\n\nMultiple (unprefixed) classnames could be added in markdown source by using character references.\nThis could make rendered user supplied markdown `code` elements appear like the rest of the page.\nThe following markdown:\n\n````markdown\n```js&#x20;xss\n```\n````\n\nWould create `<pre><code class=\"language-js xss\"></code></pre>`\nIf your page then applied `.xss` classes (or listeners in JS), those apply to this element.\nFor more info see <https://github.com/ChALkeR/notes/blob/master/Improper-markup-sanitization.md#unsanitized-class-attribute>\n\n### Patches\n\nThe bug was patched. When using regular semver, run `npm install`. For exact ranges, make sure to use `13.2.1`.\n\n### Workarounds\n\nUpdate.\n\n### References\n\n* bug introduced in https://github.com/syntax-tree/mdast-util-to-hast/commit/6fc783ae6abdeb798fd5a68e7f3f21411dde7403\n* bug fixed in https://github.com/syntax-tree/mdast-util-to-hast/commit/ab3a79570a1afbfa7efef5d4a0cd9b5caafbc5d7","state":0,"publishedAt":"2025-12-02T01:25:46+00:00","modifiedAt":"2026-09-10T03:50:31.2881543+00:00","affected":[{"ecosystem":"npm","name":"mdast-util-to-hast","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"13.0.0"},{"kind":"fixed","version":"13.2.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":null,"severity":null},{"system":"CVSS_V4","vector":"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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/syntax-tree/mdast-util-to-hast/security/advisories/GHSA-4fh9-h7wg-q85m","https://nvd.nist.gov/vuln/detail/CVE-2025-66400","https://github.com/syntax-tree/mdast-util-to-hast/commit/6fc783ae6abdeb798fd5a68e7f3f21411dde7403","https://github.com/syntax-tree/mdast-util-to-hast/commit/ab3a79570a1afbfa7efef5d4a0cd9b5caafbc5d7","https://github.com/syntax-tree/mdast-util-to-hast"],"sourceUrl":"https://github.com/advisories/GHSA-4fh9-h7wg-q85m","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-4fh9-h7wg-q85m","identifiers":["GHSA-4fh9-h7wg-q85m","CVE-2025-66400"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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