Umbraco CMS vulnerable to stored XSS via SVG File Upload

Vulnerability Description

Umbraco is an ASP.NET content management system (CMS). Starting in version 7.0.0 and prior to versions 7.15.11, 8.18.9, 10.7.0, 11.5.0, and 12.2.0, a user with access to the backoffice can upload SVG files that include scripts. If the user can trick another user to load the media directly in a browser, the scripts can be executed. Versions 7.15.11, 8.18.9, 10.7.0, 11.5.0, and 12.2.0 contain a patch for this issue. Some workarounds are available. Implement the server side file validation or serve all media from an different host (e.g cdn) than where Umbraco is hosted.

References

• https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-6xmx-85x3-4cv2
• https://docs.umbraco.com/umbraco-cms/reference/security/serverside-file-validation