Researchers find Visa contactless payment 'security flaw'
1 November 2014 Last updated at 10:41 GMT
Researchers claim they have found a security flaw with Visa contactless payment cards.
In the UK, people can make purchases up to £20 by just touching the card against a machine - without needing to enter a PIN.
However, the researchers say that a glitch means Visa's cards will approved unlimited spending if it is put through in a foreign currency.
Dan Johnson reports.