CVE-2021-32809 — ckeditor4
MEDIUMCVE-2021-32809 is a medium-severity (CVSS 5.4) Code Injection vulnerability in ckeditor4. A fix is available for ckeditor4 — see the affected versions and patch details below.
Clipboard feature vulnerability allowing to inject arbitrary HTML into the editor using paste functionality
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-32809 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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 clipboard plugin. All plugins with clipboard plugin dependency are affected:
Impact
A potential vulnerability has been discovered in CKEditor 4 Clipboard package. The vulnerability allowed to abuse paste functionality using malformed HTML, which could result in injecting arbitrary HTML into the editor. It affects all users using the CKEditor 4 plugins listed above at version >= 4.5.2.
Patches
The problem has been recognized and patched. The fix will be available in version 4.16.2.
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 Anton Subbotin (skavans) for recognizing and reporting this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ckeditor4 | ≥ 4.5.2&&< 4.16.2 | 4.16.2npm install ckeditor4@4.16.2 |
Affected Products
ckeditorckeditorfedorafedoraprojectapplication expressoraclebanking party managementoraclecommerce guided searchoraclecommerce merchandisingoracleDetection & 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 4.16.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32809 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2021-32809 in your dependencies?
Find it across npm, including transitive dependencies.