Cross-site scripting vulnerability in TinyMCE
Impact
A cross-site scripting (XSS) vulnerability was discovered in: the core parser, paste and visualchars plugins. 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 4.9.6 or lower and TinyMCE 5.1.3 or lower.
Patches
This vulnerability has been patched in TinyMCE 4.9.7 and 5.1.4 by improved parser logic and HTML sanitization.
Workarounds
The workarounds available are:
- disable the impacted plugins
- manually sanitize the content using the
BeforeSetContentevent (see below) - upgrade to either TinyMCE 4.9.7 or TinyMCE 5.1.4
Example: Manually sanitize content
editor.on('BeforeSetContent', function(e) {
var sanitizedContent = ...; // Manually sanitize content here
e.content = sanitizedContent;
});Acknowledgements
Tiny Technologies would like to thank Michał Bentkowski for discovering this vulnerability.
References
https://www.tiny.cloud/docs/release-notes/release-notes514/#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 | < 4.9.7, >= 5.0.0, < 5.1.4 | 4.9.7, 5.1.4 |
References
- https://github.com/tinymce/tinymce/security/advisories/GHSA-27gm-ghr9-4v95
- https://nvd.nist.gov/vuln/detail/CVE-2020-17480
- https://github.com/tinymce/tinymce
- https://portswigger.net/daily-swig/xss-vulnerability-patched-in-tinymce
- https://www.tiny.cloud/docs/release-notes/release-notes514/#securityfixes
- Weakness (CWE)
CWE-79- Platform
- npm
- Package
tinymce- Disclosed
- 30.01.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-27gm-ghr9-4v95 - 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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