Cross-site scripting (XSS) in the clipboard package
Impact
During a recent internal audit, we identified a Cross-Site Scripting (XSS) vulnerability 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 the following criteria:
- The Block Toolbar plugin is enabled.
- One of the following plugins is also enabled:
- General HTML Support with a configuration that permits unsafe markup.
- HTML Embed.
Patches
The problem has been recognized and patched. The fix will be available in version 43.1.1 (and above), and explicitly in version 41.3.2.
Workarounds
It's highly recommended to update to the version 43.1.1 or higher. However, if the update is not an option, we recommend disabling the block toolbar plugin.
For more information
Email us at security@cksource.com if you have any questions or comments about this advisory.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | ckeditor5 | >= 40.0.0, < 43.1.1 | 43.1.1 |
| npm package | @ckeditor/ckeditor5-clipboard | >= 40.0.0, < 43.1.1 | 43.1.1 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
ckeditor5, @ckeditor/ckeditor5-clipboard- Disclosed
- 25.09.2024
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-rgg8-g5x8-wr9v - CC BY 4.0
Vulnerability history: @ckeditor/ckeditor5-clipboard
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 09.2024 09.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 1
- Low 1
Disclosures per year
- 2024: 1
- 2025: 1
- 2026: 0
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Cross-site scripting (XSS) in the clipboard package this entry
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