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TinyMCE mXSS vulnerability in undo/redo, getContent API, resetContent API, and Autosave plugin

Moderate severity GitHub Reviewed Published Oct 19, 2023 in tinymce/tinymce • Updated Nov 15, 2023

Package

nuget TinyMCE (NuGet)

Affected versions

>= 6.0.0, < 6.7.1
< 5.10.8

Patched versions

6.7.1
5.10.8
npm tinymce (npm)
>= 6.0.0, < 6.7.1
< 5.10.8
6.7.1
5.10.8
composer tinymce/tinymce (Composer)
>= 6.0.0, < 6.7.1
< 5.10.8
6.7.1
5.10.8

Description

Impact

A mutation cross-site scripting (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 (TinyMCE 6) or the SaxParser API (TinyMCE 5) mutates the HTML maliciously, allowing an XSS payload to be executed.
​This vulnerability also impacts these related TinyMCE APIs and plugins:​

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 for discovering this vulnerability.

References

For more information

If you have any questions or comments about this advisory:

References

@mkzhx mkzhx published to tinymce/tinymce Oct 19, 2023
Published to the GitHub Advisory Database Oct 19, 2023
Reviewed Oct 19, 2023
Published by the National Vulnerability Database Oct 19, 2023
Last updated Nov 15, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS score

0.087%
(38th percentile)

Weaknesses

CVE ID

CVE-2023-45818

GHSA ID

GHSA-v65r-p3vv-jjfv

Source code

Credits

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