Cross-site scripting (XSS) in the CKEditor 5 real-time collaboration package
Impact
During a recent internal audit, we identified a Cross-Site Scripting (XSS) vulnerability in the CKEditor 5 real-time collaboration package. This vulnerability can lead to unauthorized JavaScript code execution and affects user markers, which represent users' positions within the document.
This vulnerability affects only installations with Real-time collaborative editing enabled.
Patches
The problem has been recognized and patched. The fix will be available in version 44.2.1 (and above).
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-premium-features | >= 42.0.0, < 44.2.1 | 44.2.1 |
| npm package | @ckeditor/ckeditor5-real-time-collaboration | >= 41.3.0, < 44.2.1 | 44.2.1 |
References
- https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-j3mm-wmfm-mwvh
- https://nvd.nist.gov/vuln/detail/CVE-2025-25299
- https://ckeditor.com/docs/ckeditor5/latest/features/collaboration/real-time-collaboration/real-time-collaboration.html
- https://ckeditor.com/docs/ckeditor5/latest/features/collaboration/real-time-collaboration/real-time-collaboration.html?docId=ee1dca024c9b4e44aef039f99ebe6c664
- https://github.com/ckeditor/ckeditor5
- https://github.com/ckeditor/ckeditor5/releases/tag/v44.2.1
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N- Weakness (CWE)
CWE-79, CWE-80- Platform
- npm
- Package
ckeditor5-premium-features, @ckeditor/ckeditor5-real-time-collaboration- Disclosed
- 20.02.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-j3mm-wmfm-mwvh - CC BY 4.0
Vulnerability history: ckeditor5-premium-features
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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