Be careful: a cashier’s check is not cash. While it should be backed by the FDIC, the check is not completely guaranteed by the bank.
Gotta agree with four walling: a cashier’s check can be canceled by the purchaser of that cashier’s check. All the purchaser has to do is say the check was lost, stolen, or misappropriated. In other words, lie. And I do think that we have seen one or two people lie in their financial dealings over the past year.
Of course, you can take legal action against the fraudster to get your money back — good luck.
Advice: If you get a cashier’s check from an unfamiliar party, immediately have the check verified at your bank and then have the funds immediately transferred to your account.