I have a credit card that bluescreens (some) PoS terminals. I theorize the upstream server is returning a rare error code when it's used in contactless mode, because that account's never been approved for contactless. In that case I'm going with lack of sanitizing inputs.
Terminals that only supported the first version of tap to pay in the USA often have this bug when activated by a card from this first version of tap to pay.
I have a credit card that bluescreens (some) PoS terminals. I theorize the upstream server is returning a rare error code when it's used in contactless mode, because that account's never been approved for contactless. In that case I'm going with lack of sanitizing inputs.