Simple Restrict < 1.2.9 - Contributor+ Restricted Content Disclosure via REST API
The Simple Restrict WordPress plugin before 1.2.9 does not enforce its content-restriction permission check on the REST API the way it does on the front end, relying there on a generic capability check instead of the Simple Restrict WordPress plugin before 1.2.9's own permission system, allowing users with contributor-level access or above to read the content of restricted posts and pages they were never granted access to.