My PA landlord has 1.5 months of rent for year one + 2 months of rent for year 2 = 3.5 mths $5875. I had agreed / is it legal?

My Pennslvania landlord has required (and I agreed to provide) 3.5 months of rent for security, which is reflected in two lease docs, the original and an extention.
We are in our second year of a residential lease, rent is set at $1700.00 per month, and there is $5875.00 in an escrow account. Is this legal?