CKEditor: Cross-site scripting (XSS) in the engine package

### Impact A Cross-Site Scripting (XSS) vulnerability has been discovered in the CKEditor 5 engine. This vulnerability is caused by a prototype pollution issue in the `es-toolkit` library used in the CKEditor 5 codebase. This vulnerability could lead to unauthorized JavaScript code execution when the editor processes incoming `style` attribute values. The underlying issue has been patched by the library maintainers, and the fix has been incorporated into CKEditor 5. ### Patches The problem has been recognized and patched. The fix will be available in version `48.5.1` (and above) and `47.7.4` (LTS). ### For more information Email us at [[email protected]](mailto:[email protected]) if you have any questions or comments about this advisory.

Source published

27 Oct 2026 21:05:06 UTC

Source modified

27 Oct 2026 21:15:04 UTC

Observed here

27 Oct 2026 21:46:44 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Publisher rating · HIGH