An 8 days old male infant is brought to the emergency depament with vomiting, lethargy, dehydration and features of shock. Clinical examination reveals hyperpigmentation of the genital skin and normal external genitalia. Abdominal examination is unremarkable. Blood tests revealed sodium of 124 meq/l, potassium of 7 meq/1 and hypoglycemia. Which of the following is the most likely diagnosis: