https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-12T09:46:07.656505+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/euvd-2026-262278 EUVD-2026-262278 2026-10-12T09:46:07.709984+00:00 EUVD-2026-262278 https://cve.radiocsirt.org/vuln/fkie_cve-2025-66400 fkie_cve-2025-66400 2026-10-12T09:46:07.710023+00:00

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.

 https://cve.radiocsirt.org/vuln/ghsa-4fh9-h7wg-q85m GHSA-4fh9-h7wg-q85m — mdast-util-to-hast has unsanitized class attribute 2026-10-12T09:46:07.710069+00:00

Affected: npm: mdast-util-to-hast

### Impact

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. The following markdown:

````markdown ```js xss ``` ````

Would create `<pre><code class="language-js xss"></code></pre>` If your page then applied `.xss` classes (or listeners in JS), those apply to this element. For more info see <https://github.com/ChALkeR/notes/blob/master/Improper-markup-sanitization.md#unsanitized-class-attribute>

### Patches

The bug was patched. When using regular semver, run `npm install`. For exact ranges, make sure to use `13.2.1`.

### Workarounds

Update.

### References

* bug introduced in https://github.com/syntax-tree/mdast-util-to-hast/commit/6fc783ae6abdeb798fd5a68e7f3f21411dde7403 * bug fixed in https://github.com/syntax-tree/mdast-util-to-hast/commit/ab3a79570a1afbfa7efef5d4a0cd9b5caafbc5d7