CVE-2023-48219

TinyMCE vulnerable to mutation Cross-site Scripting via special characters in unescaped text nodes

Fix

To avoid this vulnerability:

• Upgrade to TinyMCE 6.7.3 or higher for TinyMCE 6.x.
• Upgrade to TinyMCE 5.10.9 or higher for TinyMCE 5.x.

Acknowledgements

Tiny Technologies would like to thank Masato Kinugawa of Cure53 for discovering this vulnerability.

References

• TinyMCE 5.10.9 Release Notes
• TinyMCE 6.7.3 Release Notes

For more information

Email us at [email protected]
Open an issue in the TinyMCE repo

A mutation cross-site scripting (mXSS) vulnerability was discovered in TinyMCE’s core undo/redo functionality and other APIs and plugins. Text nodes within specific parents are not escaped upon serialization according to the HTML standard. If such text nodes contain a special character reserved as an internal marker, they can be combined with other HTML patterns to form malicious snippets. These snippets pass the initial sanitisation layer when the content is parsed into the editor body, but can trigger XSS when the special internal marker is removed from the content and re-parsed. Such mutations occur when serialised HTML content is processed before being stored in the undo stack, or when the following APIs and plugins are used:

• tinymce.Editor.getContent({ format: 'raw' })
• tinymce.Editor.resetContent()
• Autosave Plugin

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.

CVE-2023-48219 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.10.9, 6.7.3); upgrading removes the vulnerable code path.

Kodem intelligence

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This vulnerability has been patched in TinyMCE 6.7.3 by:

• ensuring that any unescaped text nodes which contain the special internal marker are emptied before removing the marker from the rest of the HTML, and
• removing the special internal marker from content strings passed to Editor.setContent, Editor.insertContent, and Editor.resetContent APIs to prevent them from being loaded into the editor as user-provided content.

1. What is CVE-2023-48219? CVE-2023-48219 is a medium-severity cross-site scripting (XSS) vulnerability in tinymce (npm), affecting versions < 5.10.9. It is fixed in 5.10.9, 6.7.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2023-48219? CVE-2023-48219 has a CVSS score of 6.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2023-48219?
   • tinymce (npm) (versions < 5.10.9)
   • tinymce/tinymce (composer) (versions < 5.10.9)
   • TinyMCE (nuget) (versions < 5.10.9)
4. Is there a fix for CVE-2023-48219? Yes. CVE-2023-48219 is fixed in 5.10.9, 6.7.3. Upgrade to this version or later.
5. Is CVE-2023-48219 exploitable, and should I be worried? Whether CVE-2023-48219 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
6. What actually determines whether CVE-2023-48219 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.
7. How do I fix CVE-2023-48219?
   • Upgrade tinymce to 5.10.9 or later
   • Upgrade tinymce to 6.7.3 or later
   • Upgrade tinymce/tinymce to 5.10.9 or later
   • Upgrade tinymce/tinymce to 6.7.3 or later
   • Upgrade TinyMCE to 5.10.9 or later
   • Upgrade TinyMCE to 6.7.3 or later

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