How does Voltaire satirize society's faults and failures in Candide?
A better question might be, how does it not do so?
I offer this perspective because the entire work is a satire. This starts with the title (Candide is candid, honest, but that doesn't work or fit the world) and moves through the end of the book, when Pangloss argues that the events prove that they are living in the best of all possible worlds—the complex, violent, vicious events. In between, there are many examples, but a good one would be the gap between Candide's claims of good will towards the world and how he repeatedly has Cunégonde's brother sent to the galleys when he forbids their marriage.