An incorrect authorization vulnerability in the protocol communication between the WatchGuard Authentication Gateway (aka Single Sign-On Agent) on Windows and the WatchGuard Single Sign-On Client on Windows and MacOS allows an attacker with network access to forge communications to affected components. In the event an attacker has already gained network access, they could exploit this vulnerability to retrieve authenticated usernames and group memberships from the Single Sign-On Agent or send arbitrary account and group information to the Single Sign-On Agent for their host. This vulnerability cannot be used by an attacker to gain access to user credentials.