TinyMCE Cross-Site Scripting (XSS) vulnerability in handling external SVG files through Object or Embed elements
Date: 2024-03
Affected: nuget/TinyMCE, npm/tinymce, composer/tinymce/tinymce
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2024-29881
CWE: CWE-79
CVSS: 4.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N)

### Impact A [cross-site scripting (XSS)](https://owasp.org/www-community/attacks/xss/) vulnerability was discovered in TinyMCE’s content loading and content inserting code. A SVG image could be loaded though an `object` or `embed` element and that image could potentially contain a XSS payload. ### Fix TinyMCE 6.8.1 introduced a new `convert_unsafe_embeds` option to automatically convert `object` and `embed` elements respective of their `type` attribute. From TinyMCE 7.0.0 onwards, the `convert_unsafe_embeds` option is enabled by default. ### Workarounds If you are using TinyMCE 6.8.1 or higher, set `convert_unsafe_embeds` to true. For any earlier versions, a custom NodeFilter is recommended to remove or modify any `object` or `embed` elements. This can be added using the `editor.parser.addNodeFilter` and `editor.serializer.addNodeFilter` APIs. ### Acknowledgements Tiny Technologies would like to thank Toni Huttunen of [Fraktal Oy](https://www.fraktal.fi/) for discovering this vulnerability. ### References - [TinyMCE 6.8.1](https://www.tiny.cloud/docs/tinymce/6/6.8.1-release-notes/#new-convert_unsafe_embeds-option-that-controls-whether-object-and-embed-elements-will-be-converted-to-more-restrictive-alternatives-namely-img-for-image-mime-types-video-for-video-mime-types-audio-audio-mime-types-or-iframe-for-other-or-unspecified-mime-types) - [TinyMCE 7.0.0](https://www.tiny.cloud/docs/tinymce/7/7.0-release-notes/#convert_unsafe_embeds-editor-option-is-now-defaulted-to-true


Mitigations:

Architectural layers (MAESTRO):