Nef

free5GC's NEF component is vulnerable to a denial-of-service attack where an attacker can create a PFD subscription with an attacker-controlled `notifyUri`, and when a PFD change is triggered, NEF attempts to deliver a notification to the specified URI, and if the URI is unreachable, NEF terminates the entire process, causing a service outage, and this can be triggered without authentication in version 4.2.1, making it easily exploitable.