GHSA-rgg8-g5x8-wr9v — ckeditor5
HIGHGHSA-rgg8-g5x8-wr9v is a high-severity (CVSS 7.2) Cross-site Scripting (XSS) vulnerability in ckeditor5. A fix is available for ckeditor5 — see the affected versions and patch details below.
Cross-site scripting (XSS) in the clipboard package
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-rgg8-g5x8-wr9v.
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-rgg8-g5x8-wr9v 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 379,145 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.
ckeditor5npm@ckeditor/ckeditor5-clipboardnpmDescription
Impact
During a recent internal audit, we identified a Cross-Site Scripting (XSS) vulnerability in the CKEditor 5 clipboard package. This vulnerability could be triggered by a specific user action, leading to unauthorized JavaScript code execution, if the attacker managed to insert a malicious content into the editor, which might happen with a very specific editor configuration.
This vulnerability affects only installations where the editor configuration meets the following criteria:
- The Block Toolbar plugin is enabled.
- One of the following plugins is also enabled:
- General HTML Support with a configuration that permits unsafe markup.
- HTML Embed.
Patches
The problem has been recognized and patched. The fix will be available in version 43.1.1 (and above), and explicitly in version 41.3.2.
Workarounds
It's highly recommended to update to the version 43.1.1 or higher. However, if the update is not an option, we recommend disabling the block toolbar plugin.
For more information
Email us at [email protected] if you have any questions or comments about this advisory.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ckeditor5 | ≥ 40.0.0&&< 43.1.1 | 43.1.1npm install ckeditor5@43.1.1 |
| 📦npm | @ckeditor/ckeditor5-clipboard | ≥ 40.0.0&&< 43.1.1 | 43.1.1npm install @ckeditor/ckeditor5-clipboard@43.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ckeditor5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ckeditor5 to 43.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rgg8-g5x8-wr9v 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-rgg8-g5x8-wr9v can be triaged on real exposure rather than presence alone.
Tailored to GHSA-rgg8-g5x8-wr9v. 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-rgg8-g5x8-wr9v in your dependencies?
O3 Security finds GHSA-rgg8-g5x8-wr9v across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.