Those mobile payment systems you've likely used at a coffee shop or a taco truck had security issues that could have let hackers charge you more than what you paid for.
At the Black Hat cyber security conference on Thursday, researchers from Positive Technologies discussed vulnerabilities they discovered on mobile payment readers offered from companies like PayPal, Square, SumUp and iSell.
They disclosed these issues to the companies back in April and the companies said they've since fixed these flaws.
These readers are really popular especially for small businesses.
By 2019, it's estimated that 46% all non cash payment will be done through these mobile readers.
So you can see why companies would rush to fix these security flaws.
One of the flaws allowed a rogue merchant to change what you would see on the screen during your transaction.
The researcher showed us in this cute demo video of Nyan cat flying through the screen.
But hackers might be more interested in something more than just memes.
By changing the screen display a hacker could have charged you $1.23 while on the display showing that you are actually paying $1 as the researcher showed in another demo video.
Even though the flaws are fixed, if you're really concerned your best protection is to stick with the security chip on your credit card instead of using the magnetic stripe.