CVE-2023-45818: Cross-site Scripting vulnerability in TinyMCE undo/redo, getContent API, resetContent API, and Autosave plugin
First published: Thu Oct 19 2023(Updated: )
### Impact A [mutation cross-site scripting](https://researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-applications_by_using_innerHTML_mutations) (mXSS) vulnerability was discovered in TinyMCE’s core undo and redo functionality. When a carefully-crafted HTML snippet passes the XSS sanitisation layer, it is manipulated as a string by internal trimming functions before being stored in the undo stack. If the HTML snippet is restored from the undo stack, the combination of the string manipulation and reparative parsing by either the browser's native [DOMParser API](https://developer.mozilla.org/en-US/docs/Web/API/DOMParser) (TinyMCE 6) or the [SaxParser API](https://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser/) (TinyMCE 5) mutates the HTML maliciously, allowing an XSS payload to be executed. This vulnerability also impacts these related TinyMCE APIs and plugins: * [`tinymce.Editor.getContent({ format: 'raw' })`](https://tiny.cloud/docs/tinymce/6/apis/tinymce.editor/#getContent) * [`tinymce.Editor.resetContent()`](https://tiny.cloud/docs/tinymce/6/apis/tinymce.editor/#resetContent) * [Autosave Plugin](https://tiny.cloud/docs/tinymce/6/autosave/) ### Patches This vulnerability has been patched in TinyMCE 5.10.8 and TinyMCE 6.7.1 by ensuring HTML is trimmed using node-level manipulation instead of string manipulation. ### Fix To avoid this vulnerability: * Upgrade to TinyMCE 5.10.8 or higher for TinyMCE 5.x. * Upgrade to TinyMCE 6.7.1 or higher for TinyMCE 6.x. ### Acknowledgements Tiny Technologies would like to thank Masato Kinugawa of [Cure53](https://cure53.de/) for discovering this vulnerability. ### References * [TinyMCE 5.10.8 Release Notes](https://tiny.cloud/docs/release-notes/release-notes5108/) * [TinyMCE 6.7.1 Release Notes](https://tiny.cloud/docs/tinymce/6/6.7.1-release-notes/) ### For more information If you have any questions or comments about this advisory: * Email us at <infosec@tiny.cloud> * Open an issue in the [TinyMCE repo](https://github.com/tinymce/tinymce/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc)
Credit: security-advisories@github.com security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| composer/tinymce/tinymce | <5.10.8 | 5.10.8 |
| nuget/TinyMCE | <5.10.8 | 5.10.8 |
| npm/tinymce | <5.10.8 | 5.10.8 |
| composer/tinymce/tinymce | >=6.0.0<6.7.1 | 6.7.1 |
| nuget/TinyMCE | >=6.0.0<6.7.1 | 6.7.1 |
| npm/tinymce | >=6.0.0<6.7.1 | 6.7.1 |
| TinyMCE | <5.10.8 | |
| TinyMCE | >=6.0.0<6.7.1 |
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Reference Links
- https://github.com/tinymce/tinymce/security/advisories/GHSA-v65r-p3vv-jjfv
- https://researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-applications_by_using_innerHTML_mutations
- https://tiny.cloud/docs/release-notes/release-notes5108/#securityfixes
- https://tiny.cloud/docs/tinymce/6/6.7.1-release-notes/#security-fixes
- https://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser/
- https://nvd.nist.gov/vuln/detail/CVE-2023-45818
- https://github.com/advisories/GHSA-v65r-p3vv-jjfv (Advisory)
Frequently Asked Questions
What is the impact of CVE-2023-45818?
CVE-2023-45818 is a mutation cross-site scripting (mXSS) vulnerability in TinyMCE's core undo and redo functionality.
How can an attacker exploit CVE-2023-45818?
An attacker can exploit CVE-2023-45818 by crafting a malicious HTML snippet that can execute unauthorized scripts in the user's browser.
What is the severity rating of CVE-2023-45818?
CVE-2023-45818 has a severity rating of 6.1 (medium).
What software versions are affected by CVE-2023-45818?
Versions up to 5.10.8 of tinymce/tinymce, TinyMCE, and tinymce npm package, as well as versions between 6.0.0 and 6.7.1 of tinymce/tinymce, TinyMCE, and tinymce npm package are affected by CVE-2023-45818.
How can I fix CVE-2023-45818?
To fix CVE-2023-45818, update to version 5.10.8 of tinymce/tinymce, TinyMCE, and tinymce npm package, or update to a version between 6.0.0 and 6.7.1 of tinymce/tinymce, TinyMCE, and tinymce npm package.
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