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Cross-site scripting vulnerability in TinyMCE plugins

Moderate severity GitHub Reviewed Published Nov 1, 2021 in tinymce/tinymce • Updated Jan 3, 2024

Package

nuget TinyMCE (NuGet)

Affected versions

< 5.10.0

Patched versions

5.10.0
pip django-tinymce (pip)
< 3.4.0
3.4.0
npm tinymce (npm)
< 5.10.0
5.10.0
composer tinymce/tinymce (Composer)
< 5.10.0
5.10.0

Description

Impact

A cross-site scripting (XSS) vulnerability was discovered in the URL processing logic of the image and link plugins. The vulnerability allowed arbitrary JavaScript execution when updating an image or link using a specially crafted URL. This issue only impacted users while editing and the dangerous URLs were stripped in any content extracted from the editor. This impacts all users who are using TinyMCE 5.9.2 or lower.

Patches

This vulnerability has been patched in TinyMCE 5.10.0 by improved sanitization logic when updating URLs in the relevant plugins.

Workarounds

To work around this vulnerability, either:

  • Upgrade to TinyMCE 5.10.0 or higher
  • Disable the image and link plugins

Acknowledgements

Tiny Technologies would like to thank Yakir6 for discovering this vulnerability.

References

https://www.tiny.cloud/docs/release-notes/release-notes510/#securityfixes

For more information

If you have any questions or comments about this advisory:

References

@lnewson lnewson published to tinymce/tinymce Nov 1, 2021
Reviewed Nov 1, 2021
Published to the GitHub Advisory Database Nov 2, 2021
Last updated Jan 3, 2024

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

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(78th percentile)

Weaknesses

Windows Shortcut Following (.LNK)

The product, when opening a file or directory, does not sufficiently handle when the file is a Windows shortcut (.LNK) whose target is outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. Learn more on MITRE.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2024-21910

GHSA ID

GHSA-r8hm-w5f7-wj39

Source code

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