This issue was addressed by improving Face ID machine learning models. This issue is fixed in iOS 13. A 3D model constructed to look like the enrolled user may authenticate via Face ID.
[
{
"product": "iOS",
"vendor": "Apple",
"versions": [
{
"lessThan": "iOS 13",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
}
]