How severe is GHSA-j3mm-wmfm-mwvh?

No CVSS score has been assigned to GHSA-j3mm-wmfm-mwvh yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-j3mm-wmfm-mwvh?

GHSA-j3mm-wmfm-mwvh affects the following packages: @ckeditor/ckeditor5-real-time-collaboration (npm), ckeditor5-premium-features (npm). Ecosystems affected: npm.

How do I fix GHSA-j3mm-wmfm-mwvh?

Update @ckeditor/ckeditor5-real-time-collaboration to 44.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j3mm-wmfm-mwvh is resolved across your whole dependency graph.

How do I detect GHSA-j3mm-wmfm-mwvh in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @ckeditor/ckeditor5-real-time-collaboration, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-j3mm-wmfm-mwvh if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is GHSA-j3mm-wmfm-mwvh actively exploited in the wild?

No public exploit code has been indexed for GHSA-j3mm-wmfm-mwvh yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-j3mm-wmfm-mwvh?

GHSA-j3mm-wmfm-mwvh has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 49th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-j3mm-wmfm-mwvh?

GHSA-j3mm-wmfm-mwvh is classified as Cross-site Scripting (XSS) (CWE-79), CWE-80 (CWE-80). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-j3mm-wmfm-mwvh published, and has it been updated?

GHSA-j3mm-wmfm-mwvh was published on February 20, 2025 and was last updated on February 20, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

Cross-site scripting (XSS) in the CKEditor 5 real-time collaboration packageGHSA-j3mm-wmfm-mwvh

GHSA-j3mm-wmfm-mwvh is a Cross-site Scripting (XSS) vulnerability in @ckeditor/ckeditor5-real-time-collaboration. A fix is available for @ckeditor/ckeditor5-real-time-collaboration — see the affected versions and patch details below.

Also known asCVE-2025-25299

Published

Feb 20, 2025

Updated

Feb 20, 2025

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs49th percentile — riskier than 49% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

11other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@ckeditor/ckeditor5-real-time-collaborationnpm

174Kdownloads / week

ckeditor5-premium-featuresnpm

118Kdownloads / week

Description

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 [email protected] if you have any questions or comments about this advisory.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@ckeditor/ckeditor5-real-time-collaboration`	≥ 41.3.0&&< 44.2.1	44.2.1`npm install @ckeditor/ckeditor5-real-time-collaboration@44.2.1`
📦npm	`ckeditor5-premium-features`	≥ 42.0.0&&< 44.2.1	44.2.1`npm install ckeditor5-premium-features@44.2.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @ckeditor/ckeditor5-real-time-collaboration, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @ckeditor/ckeditor5-real-time-collaboration to 44.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j3mm-wmfm-mwvh is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### 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](https://ckeditor.com/docs/ckeditor5/latest/features/collaboration/real-time-collaboration/real-time-collaboration.html) enabled. ### Patches The problem has been recognized and patched. The fix will be available

O3 Security · Impact-Aware SCA

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