GHSA-fq6h-4g8v-qqvm is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in ckeditor4. A fix is available for ckeditor4 — see the affected versions and patch details below.
CKEditor4 Cross-site Scripting vulnerability caused by incorrect CDATA detection
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-fq6h-4g8v-qqvm.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-fq6h-4g8v-qqvm plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
ckeditor4npmDescription
Affected packages
The vulnerability has been discovered in the core HTML parsing module and may affect all editor instances that:
- Enabled full-page editing mode,
- or enabled CDATA elements in Advanced Content Filtering configuration (defaults to
scriptandstyleelements).
Impact
A potential vulnerability has been discovered in CKEditor 4 HTML processing core module. The vulnerability allowed to inject malformed HTML content bypassing Advanced Content Filtering mechanism, which could result in executing JavaScript code. An attacker could abuse faulty CDATA content detection and use it to prepare an intentional attack on the editor. It affects all users using the CKEditor 4 at version < 4.24.0-lts.
Patches
The problem has been recognized and patched. The fix will be available in version 4.24.0-lts.
For more information
Email us at [email protected] if you have any questions or comments about this advisory.
Acknowledgements
The CKEditor 4 team would like to thank Michal Frýba from ALEF NULA for recognizing and reporting this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ckeditor4 | all versions | 4.24.0-ltsnpm install ckeditor4@4.24.0-lts |
| 🐘Packagist | ckeditor/ckeditor | all versions | 4.24.0composer require ckeditor/ckeditor:^4.24.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ckeditor4, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ckeditor4 to 4.24.0-lts or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fq6h-4g8v-qqvm is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-fq6h-4g8v-qqvm can be triaged on real exposure rather than presence alone.
Tailored to GHSA-fq6h-4g8v-qqvm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-fq6h-4g8v-qqvm in your dependencies?
O3 Security finds GHSA-fq6h-4g8v-qqvm across npm, Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.