The customer experienced the issue with incorrect handling lack of permissions exception with embedded content. This exception should be handled as in case of related content (defined using Single/Multi-Relation field) when an anonymous user tries to open the article with restricted embedded content, this content isn't rendered at all. Even simpler, just redirect to the login page.

Steps to reproduce

1. Create new article, for e.g. Article A
2. Create new article, for e.g. Article B
3. Edit Article A, in the Online editor (for instance in Body field), embed Article B.
4. Go to Setup -> Sections, choose Restricted
5. Add Article B to Restricted section
6. Try to open Article A on the front-end as an anonymous user. You will get the exception:

   An exception has been thrown during the rendering of a template ("User does not have access to 'read' 'content' with: contentId 'xxx'") in "EzPublishCoreBundle::content_fields.html.twig".