Summary
Cross-site scripting vulnerability in TinyMCE
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 [email protected]
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.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This vulnerability has been patched in TinyMCE 4.9.7 and 5.1.4 by improved parser logic and HTML sanitization.
Frequently Asked Questions
- What is CVE-2020-17480? CVE-2020-17480 is a high-severity cross-site scripting (XSS) vulnerability in tinymce (npm), affecting versions < 4.9.7. It is fixed in 4.9.7, 5.1.4. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of tinymce are affected by CVE-2020-17480? tinymce (npm) versions < 4.9.7 is affected.
- Is there a fix for CVE-2020-17480? Yes. CVE-2020-17480 is fixed in 4.9.7, 5.1.4. Upgrade to this version or later.
- Is CVE-2020-17480 exploitable, and should I be worried? Whether CVE-2020-17480 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-17480 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-17480?
- Upgrade
tinymceto 4.9.7 or later - Upgrade
tinymceto 5.1.4 or later
- Upgrade