XSS in TinyMCE
Impact
A cross-site scripting (XSS) vulnerability was discovered in: the core parser and media plugin. 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 4.9.9 or lower and TinyMCE 5.2.1 or lower.
Patches
This vulnerability has been patched in TinyMCE 4.9.10 and 5.2.2 by improved HTML parsing and sanitization logic.
Workarounds
The workarounds available are:
- disable the media plugin and manually sanitize CDATA content (see below) or
- upgrade to either TinyMCE 4.9.10 or TinyMCE 5.2.2
Example: Manually strip CDATA elements
setup: function(editor) {
editor.on('PreInit', function() {
editor.parser.addNodeFilter('#cdata', function(nodes) {
for (var i = 0; i < nodes.length; i++) {
nodes[i].remove();
}
});
});
}Acknowledgements
Tiny Technologies would like to thank Michał Bentkowski and intivesec for discovering these vulnerabilities.
References
https://www.tiny.cloud/docs/release-notes/release-notes522/#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 | < 4.9.10, >= 5.0.0, < 5.2.2 | 4.9.10, 5.2.2 |
References
- Weakness (CWE)
CWE-79- Platform
- npm
- Package
tinymce- Disclosed
- 11.05.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-c78w-2gw7-gjv3 - 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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