The Drupal core Media module allows embedding internal and external media in content fields. In certain circumstances, the filter could allow an unprivileged user to inject HTML into a page when it is accessed by a trusted user with permission to embed media. In some cases, this could lead to cross-site scripting.
This advisory is not covered by [Drupal Steward](/steward).
Also see [Entity Embed - Moderately critical - Cross Site Request Forgery - SA-CONTRIB-2021-028](https://www.drupal.org/sa-contrib-2021-028) which addresses a similar vulnerability for that module.
*Updated 18:15 UTC to clarify text.*