CKEditor 5 has Cross-site Scripting (XSS) in the HTML Support package
Impact
A Cross-Site Scripting (XSS) vulnerability has been discovered in the General HTML Support feature. This vulnerability could be triggered by inserting specially crafted markup, leading to unauthorized JavaScript code execution, if the editor instance used an unsafe General HTML Support configuration.
This vulnerability affects only installations where the editor configuration meets the following criteria:
- General HTML Support is enabled,
- General HTML Support configuration allows inserting unsafe markup (see Security section to learn more).
Patches
The problem has been recognized and patched. The fix will be available in version 47.6.0 (and above).
Workarounds
CKEditor 5 recommends configuring General HTML Support securely to ensure that unsafe content is not accepted. Please refer to the Security section for detailed guidance.
Credits
CKEditor 5 would like to thank:
- Emilio Kevin
- Jeongwoo Lee, Younsoung Kim, Minseok Kim and Jinyeong Kim from ENKI Whitehat
for responsibly reporting this vulnerability.
For more information
Email us at security@cksource.com if you have any questions or comments about this advisory.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | ckeditor5 | >= 29.0.0, < 47.6.0 | 47.6.0 |
| npm package | @ckeditor/ckeditor5-html-support | >= 29.0.0, < 47.6.0 | 47.6.0 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
ckeditor5, @ckeditor/ckeditor5-html-support- Disclosed
- 04.03.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-jrqm-vmqc-gm93 - CC BY 4.0
Vulnerability history: ckeditor5
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 09.2024 03.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
- Low 1
Disclosures per year
- 2024: 1
- 2025: 1
- 2026: 1
-
CKEditor 5 has Cross-site Scripting (XSS) in the HTML Support package this entry
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