Skip to content

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

Moderate severity GitHub Reviewed Published Nov 15, 2023 in tinymce/tinymce • Updated Nov 15, 2023

Package

nuget TinyMCE (NuGet)

Affected versions

< 5.10.9
>= 6.0.0, < 6.7.3

Patched versions

5.10.9
6.7.3
npm tinymce (npm)
< 5.10.9
>= 6.0.0, < 6.7.3
5.10.9
6.7.3
composer tinymce/tinymce (Composer)
< 5.10.9
>= 6.0.0, < 6.7.3
5.10.9
6.7.3

Description

Impact

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:

Patches

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.

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

For more information

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

References

@mkzhx mkzhx published to tinymce/tinymce Nov 15, 2023
Published to the GitHub Advisory Database Nov 15, 2023
Reviewed Nov 15, 2023
Published by the National Vulnerability Database Nov 15, 2023
Last updated Nov 15, 2023

Severity

Moderate
6.1
/ 10

CVSS base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weaknesses

CVE ID

CVE-2023-48219

GHSA ID

GHSA-v626-r774-j7f8

Source code

Credits

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.