For the second time this year, the technology behind the popular Oyster Card has been compromised after Dutch researchers unearthed yet another security flaw, an issue that could affect more than 17 million cards.
Dr Bart Jacobs of Radboud University in Holland did a demonstration with a bog-standard laptop and managed to clone a swipe access card to a Dutch public building which uses the same MiFare technology.
Dr Jacobs and his team then travelled to London and travelled on the underground for free for 24 hours to highlight the massive problem that this could cause on the underground.
The problem is compounded by the fact that the criminal does not need to have physical access to the card(s) to be able to access the information on it; a proximity data sniffer is more than enough to gather a card user's information.
The MiFare Chip was created back in 1994 by Global Electronics giant Philips and currently roughly two billions have been sold worldwide.
The Dutch government, which Dr Jacobs first informed, has swiftly replaced the cards that were provided to its 120,000 civil servants to access its buildings.
Back in March, a trio of young computer geeks from the university of Virginia managed to crack the MiFare security system.