Privilege escalation in RBAC system

A privilege escalation vulnerability impacting the Google Exposure Notification Verification Server (versions prior to 0.23.1), allows an attacker who (1) has UserWrite permissions and (2) is using a carefully crafted request or malicious proxy, to create another user with higher privileges than their own. This occurs due to insufficient checks on the allowed set of permissions. The new user creation event would be captured in the Event Log.

An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications) protocol through 2020-09-29, as used in COVID-19 applications on Android and iOS. It allows a user to be put in a position where he or she can be coerced into proving or disproving an exposure notification, because of the persistent state of a private framework.