A vulnerability in free5GC, an open-source 5G core network implementation, causes a nil-pointer dereference panic in the NEF PATCH handler for PFD management. The issue occurs when upstream UDR calls fail and the consumer wrapper returns an error with nil ProblemDetails. The handler incorrectly attempts to read the Cause field from a nil pointer, causing a panic that results in HTTP 500 responses instead of proper error handling. This affects versions prior to 4.2.2 and has been fixed in the latest release.