CKEditor 5 is a modern JavaScript rich-text editor with an MVC architecture. ckeditor5 and ckeditor5-clipboard versions 46.0.0 through 46.0.2 and 44.2.0 through 45.2.1 contain a Cross-Site Scripting (XSS) vulnerability. Ability to exploit could be triggered by a specific user action (leading to unauthorized JavaScript code execution) if the attacker managed to insert a malicious content into the editor, which might happen with a very specific editor configuration. This vulnerability affects installations where the editor configuration meets one of the following criteria: the HTML embed plugin is enabled, or there is a custom plugin introducing an editable element where view RawElement is enabled. This issue is fixed in versions 45.2.2 and 46.0.3 of both ckeditor5 and ckeditor5-clipboard.

Affected: npm: ckeditor5, npm: @ckeditor/ckeditor5-clipboard

### Impact A Cross-Site Scripting (XSS) vulnerability has been discovered in the CKEditor 5 clipboard package. This vulnerability could be triggered by a specific user action, leading to unauthorized JavaScript code execution, if the attacker managed to insert a malicious content into the editor, which might happen with a very specific editor configuration.

This vulnerability affects **only** installations where the editor configuration meets one of the following criteria: - [HTML embed plugin](https://ckeditor.com/docs/ckeditor5/latest/features/html/html-embed.html) is enabled - Custom plugin introducing editable element which implements view [`RawElement`](https://ckeditor.com/docs/ckeditor5/latest/api/module_engine_view_rawelement-ViewRawElement.html) is enabled

### Patches The problem has been recognized and patched. The fix will be available in version 46.0.3 (and above), and explicitly in version 45.2.2.

### For more information Email us at [security@cksource.com](mailto:security@cksource.com) if you have any questions or comments about this advisory.