An array index out of bounds vulnerability in the AMF component of free5GC v4.0.1 allows remote attackers to cause a denial of service via a crafted 5GS Mobile Identity in a NAS Registration Request message. The issue occurs in the GetSUCI method (NAS_MobileIdentity5GS.go) when accessing index 5 of a 5-element array, leading to a runtime panic and AMF crash.