CVE-2020-12648: Cross-site scripting vulnerability in TinyMCE
Summary
CVE-2020-12648: Cross-site scripting vulnerability in TinyMCE. Affects tinymce across 2 version ranges.
< 4.9.11
>= 5.0.0, < 5.4.1
Fixed in 4.9.11 or 5.4.1, depending on the release line you run. How to fix ↓
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Background
TinyMCE is a popular open-source WYSIWYG editor used for embedding rich text editing capabilities into web applications. It allows users to create and edit content with a familiar word processor-like interface. However, versions 4.9.10 and lower of TinyMCE, as well as versions 5.4.0 and lower, are vulnerable to a cross-site scripting (XSS) attack.
Vulnerability Detail
The XSS vulnerability in TinyMCE arises from a flaw in the core parser. Attackers can exploit this vulnerability by inserting specially crafted content into the editor via the clipboard or APIs. This allows them to execute arbitrary JavaScript code within the context of the affected user's browser. The impact of this vulnerability is significant, as it affects all users of the vulnerable versions of TinyMCE.
How To Fix
Latest published version: 8.10.0 as of 23 Oct 2026
npm install tinymce@8.10.0Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 4.9.114.9.11npm install tinymce@4.9.11 -
>= 5.0.0, < 5.4.15.4.1npm install tinymce@5.4.1
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
Alternatively, you can enable the media plugin, which overrides the default parsing behavior for iframes. Another workaround involves updating the parsing schema rules for iframes. Here is an example of how to change the default schema for iframes:
setup: function(editor) {
editor.on('PreInit', function() {
editor.schema.getSpecialElements()['iframe'] = /<\/iframe[^>]*>/gi;
});
}
Conclusion
The cross-site scripting vulnerability in TinyMCE can be mitigated by upgrading to the patched versions or implementing the provided workarounds. It is crucial to promptly address this vulnerability to prevent potential security breaches. For further assistance or support in vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for tinymce →
FAQ
The vulnerability allows attackers to execute arbitrary JavaScript code in the context of the affected user's browser, potentially leading to unauthorized access, data theft, or other malicious activities.
TinyMCE versions 4.9.10 and lower, as well as versions 5.4.0 and lower, are affected by this vulnerability.
There are no known public exploits for this vulnerability at the time of this advisory.
Yes, this vulnerability has been patched in TinyMCE 4.9.11 and 5.4.1 by improving the HTML parsing and sanitization logic.
This vulnerability was discovered by George Steketee and Chris Davis at Bishop Fox.
References
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