Cross-site scripting (XSS) in the CKEditor 5 real-time collaboration package

Description

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.

Recommendation

Update the @ckeditor/ckeditor5-real-time-collaboration package to the latest compatible version. Followings are version details:

• Affected version(s): >= 41.3.0, <= 44.2.0
• Patched version(s): 44.2.1

References

• GHSA-j3mm-wmfm-mwvh
• ckeditor.com
• CVE-2025-25299
• CWE-79
• CWE-80
• CAPEC-310
• OWASP 2021-A3
• OWASP 2021-A6

Related Issues

• CKEditor 5 cross-site scripting (XSS) vulnerability in the clipboard package - CVE-2025-58064
• CKEditor 5 cross-site scripting (XSS) vulnerability in the clipboard package - ckeditor5 - CVE-2025-58064
• CKEditor 5 has Cross-site Scripting (XSS) in the HTML Support package - CVE-2026-28343
• CKEditor 5 has Cross-site Scripting (XSS) in the HTML Support package - @ckeditor/ckeditor5-html-support - CVE-2026-28343

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Tags:

npm

@ckeditor/ckeditor5-real-time-collaboration