CVE-2025-25299: 
JavaScript vulnerability analysis and mitigation

CKEditor 5, a modern JavaScript rich-text editor with an MVC architecture, was found to contain a Cross-Site Scripting (XSS) vulnerability in its real-time collaboration package (CVE-2025-25299). The vulnerability was discovered during a recent internal audit and affects installations with Real-time collaborative editing enabled. The issue specifically impacts user markers, which represent users' positions within the document (MITRE, GitHub Advisory).

The vulnerability is classified as High severity and is identified as CWE-80. It affects CKEditor 5 real-time collaboration package versions v41.3.0 through v44.2.0 and ckeditor5-premium-features versions v42.0.0 through v44.2.0. The vulnerability specifically manifests in the real-time collaboration feature's user marker functionality, which could lead to unauthorized JavaScript code execution (GitHub Advisory).

The vulnerability can lead to unauthorized JavaScript code execution when exploited. This could potentially allow attackers to execute arbitrary scripts, compromising the security of the collaborative editing environment. However, the impact is limited to installations that have Real-time collaborative editing enabled (GitHub Advisory).

The vulnerability has been patched in version 44.2.1 and above. Users are advised to upgrade to this version or later to address the security issue. There are no known workarounds for this vulnerability other than upgrading to the patched version (GitHub Release).