Improper Access Control
In versions of Drupal 8 core 8.4.0-alpha1 and all versions prior to 8.3.7; There is a vulnerability in the entity access system that could allow unwanted access to view, create, update, or delete entities. This only affects entities that do not use or do not have UUIDs, and entities that have different access restrictions on different revisions of the same entity.
CWE-284 - Improper Access Control
Listed 5th in the 'OWASP Top Ten', improper (or broken) access control attacks are a fundamental type of vulnerability. This includes a broad range of design flaws that enable users to act outside of their intended permissions. They can use these privileges to gain access to restricted files and functionality such as accessing restricted information, falsifying records, destroying data, or executing commands.