Commentary Purg XX 10-12

Virgil addresses Plutus, standing over the avaricious in the fourth Circle of hell, as 'maladetto lupo' (accursèd wolf -- [Inf VII 8]); the she-wolf (lupa) who blocks Dante's upward path in [Inf I 49-54] is widely understood to represent the sin of avarice.  Here there can be no doubt: the poet apostrophizes that sin as being the most widespread among mortals.