CVE-2026-44319 free5GC: NEF crashes via logger.Fatal on PFD notification delivery failure (attacker-controlled notifyUri)

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF terminates the entire process when a stored PFD-subscription notifyUri cannot be reached. In PfdChangeNotifier.FlushNotifications, the notifier calls NnefPFDmanagementNotify... and on any delivery error...