Cross-site scripting vulnerability in TinyMCE
Impact
A cross-site scripting (XSS) vulnerability was discovered in the core parser. The vulnerability allowed arbitrary JavaScript execution when inserting a specially crafted piece of content into the editor via the clipboard or APIs. This impacts all users who are using TinyMCE 4.9.10 or lower and TinyMCE 5.4.0 or lower.
Patches
This vulnerability has been patched in TinyMCE 4.9.11 and 5.4.1 by improved HTML parsing and sanitization logic.
Workarounds
The workarounds available are:
- upgrade to either TinyMCE 4.9.11 or TinyMCE 5.4.1 or
- enable the media plugin, which overrides the default parsing behaviour for iframes or
- add the following workaround to update the parsing schema rules for iframes:
Example: Change the default schema for iframes
setup: function(editor) {
editor.on('PreInit', function() {
editor.schema.getSpecialElements()['iframe'] = /</iframe[^>]*>/gi;
});
}Acknowledgements
Tiny Technologies would like to thank George Steketee and Chris Davis at Bishop Fox for discovering this vulnerability.
References
https://www.tiny.cloud/docs/release-notes/release-notes54/#securityfixes
For more information
If you have any questions or comments about this advisory:
- Open an issue in the TinyMCE repo
- Email us at infosec@tiny.cloud
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | tinymce | < 4.9.11, >= 5.0.0, < 5.4.1 | 4.9.11, 5.4.1 |
References
- https://github.com/tinymce/tinymce/security/advisories/GHSA-vrv8-v4w8-f95h
- https://github.com/tinymce/tinymce/pull/5843
- https://github.com/tinymce/tinymce/commit/2b71c922214d388838d930806207a66c14e80f63
- https://github.com/tinymce/tinymce/commit/696e43658dc9750ec24fdc4650bd2be9653daf5b
- https://github.com/tinymce/tinymce
- https://www.tiny.cloud/docs/release-notes/release-notes54/#securityfixes
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
tinymce- Disclosed
- 11.08.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-vrv8-v4w8-f95h - CC BY 4.0
Vulnerability history: tinymce
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
- 20
- First → latest
- 01.2020 06.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 5
- Medium 14
- Low 1
Disclosures per year
- 2020: 3
- 2021: 5
- 2022: 1
- 2023: 3
- 2024: 4
- 2025: 0
- 2026: 4
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