# CVE-2025-25299: CKEditor 5 cross-site scripting in real-time collaboration

Source: https://junglewise.ai/threats/cve-2025-25299-ckeditor-5-cross-site-scripting-in-real-time-collaboration  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-02-20. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2025-25299 · Severity: medium · CVSS 4 · Published 2025-02-20

CKEditor 5 is a popular rich-text editor used in web applications to allow users to create and edit documents. A cross-site scripting (XSS) vulnerability in its real-time collaboration feature allows attackers to inject malicious JavaScript code that executes in users' browsers, potentially leading to session hijacking, credential theft, or unauthorized document manipulation. The vulnerability only affects systems with real-time collaborative editing enabled.

Technologies: [CKEditor 5](https://junglewise.ai/threats/technologies/ckeditor-5). Vendors: [CKEditor](https://junglewise.ai/threats/vendors/ckeditor), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2025-25299 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-25299 being exploited in the wild.

**How severe is CVE-2025-25299?** Medium severity, with a CVSS score of 4, published 20 February 2025.

**Which products and versions are affected?** CKEditor 5 v41.3.0 to v44.2.0; @ckeditor/ckeditor5-real-time-collaboration (npm) SEMVER:introduced=41.3.0,fixed=44.2.1; ckeditor5-premium-features (npm) SEMVER:introduced=42.0.0,fixed=44.2.1.

**Is there a fix for CVE-2025-25299?** Yes. @ckeditor/ckeditor5-real-time-collaboration (npm): upgrade to 44.2.1 or later; ckeditor5-premium-features (npm): upgrade to 44.2.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-25299 attacked?** It is attacked over the network.

**Am I affected by CVE-2025-25299?** Check whether you run CKEditor 5, @ckeditor/ckeditor5-real-time-collaboration (npm) or ckeditor5-premium-features (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @ckeditor/ckeditor5-real-time-collaboration (npm): upgrade to 44.2.1 or later

  ```sh
  npm install @ckeditor/ckeditor5-real-time-collaboration@44.2.1
  ```

- ckeditor5-premium-features (npm): upgrade to 44.2.1 or later

  ```sh
  npm install ckeditor5-premium-features@44.2.1
  ```


## Technical details

A cross-site scripting (XSS) vulnerability exists in the CKEditor 5 real-time collaboration package, specifically affecting the handling of user markers that represent user positions within shared documents. The vulnerability stems from improper neutralization of script-related HTML tags (CWE-80), allowing attackers to inject malicious JavaScript through document markers. Attack vectors include network-based exploitation without authentication or user interaction required. An attacker can execute arbitrary JavaScript in the context of collaborative editing sessions. The vulnerability is patched in version 44.2.1 and above for both the @ckeditor/ckeditor5-real-time-collaboration package (v41.3.0–v44.2.0 affected) and ckeditor5-premium-features package (v42.0.0–v44.2.0 affected).

## Affected products

- CKEditor CKEditor 5 v41.3.0 to v44.2.0

## Identifiers

- CVE-2025-25299
- GHSA-j3mm-wmfm-mwvh

## Timeline

- 2025-02-20: disclosed: Vulnerability disclosed via GHSA-j3mm-wmfm-mwvh and CVE-2025-25299
- 2025-02-20: patched: Patched in version 44.2.1 and above

## References

- [https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-j3mm-wmfm-mwvh](https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-j3mm-wmfm-mwvh)

## Related threats

- [CKEditor 5 cross-site scripting in HTML Support](https://junglewise.ai/threats/cve-2026-28343-ckeditor-5-cross-site-scripting-in-html-support)
- [CKEditor 5 cross-site scripting in clipboard package](https://junglewise.ai/threats/cve-2025-58064-ckeditor-5-cross-site-scripting-in-clipboard-package)