Impact

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.

Workaround

Implement the server side file validation
https://docs.umbraco.com/umbraco-cms/reference/security/serverside-file-validation

or

Serve all media from an different host (e.g cdn) that where umbraco is hosted