CVE-2025-25299: Cross-site scripting (XSS) in the 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.
Other sources
CKEditor 5 is a modern JavaScript rich-text editor with an MVC architecture. During a recent internal audit, a Cross-Site Scripting (XSS) vulnerability was discovered in the CKEditor 5 real-time collaboration package. This vulnerability affects user markers, which represent users' positions within the document. It can lead to unauthorized JavaScript code execution, which might happen with a very specific editor and token endpoint configuration. This vulnerability affects only installations with Real-time collaborative editing enabled. The problem has been recognized and patched. The fix is available in version 44.2.1 (and above). Users are advised to upgrade. There are no known workarounds for this vulnerability.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2025-25299?
CVE-2025-25299 is classified as a high-severity Cross-Site Scripting (XSS) vulnerability in CKEditor 5.
How do I fix CVE-2025-25299?
To fix CVE-2025-25299, update CKEditor 5 to version 44.2.1 or later.
Which versions of CKEditor 5 are affected by CVE-2025-25299?
CVE-2025-25299 affects versions of CKEditor 5 prior to 44.2.1.
What is the impact of CVE-2025-25299 on users?
CVE-2025-25299 can allow an attacker to execute arbitrary JavaScript in the context of the affected user's session.
Is CVE-2025-25299 related to real-time collaboration features?
Yes, CVE-2025-25299 specifically affects the real-time collaboration package in CKEditor 5.