Edit

CdmVaadinAuthentication has been implemented (#4844) to overcome the problem of parallel login into multiple vaadin UIs.

The implemented solution seems to work but it should be considered if it would be a more proper strategy to implement a "own SecurityContextHolderStrategy and plug it into the SecurityContextHolder when the application starts up. The strategy would then access the current VaadinSession to store and retrieve the security context." as suggested in https://vaadin.com/blog/-/blogs/a-hybrid-approach-to-spring-security-in-vaadin-applications