Hackers are at it again. This time, allegedly targeting Starbucks customers who pay using the mobile app.

Dr. Grandon Gill, a cybersecurity professor at the University of South Florida, says the breach is a big deal.

"Mobile apps are very important to Starbucks because one sixth of their business takes place through this mobile app," said Gill.

Gill says the gift cards aren't an issue, but they can become vulnerable when customers allow cards to be reloaded through auto debit.

"It creates another layer between the financial transaction and the bank that ultimately pays the transaction, and as a consequence it's less likely to produce red flags at the bank," said Gill.

Megan Marquetti uses the card and mobile app, and the news of the alleged hack has her concerned.

"Because it's my account from my phone which makes it easier to pay, but if someone hacks into it, they can easily get into my stuff," said Marquetti.

The hack has others worried about their cybersecurity.

"Yeah, it's scary how vulnerable and easy it is for someone to just come in and clear out your bank account," said Abbigayle Singletary.

So the best advice comes from the experts: Don't throw away your gift cards or stop using payment apps. Just don't give any company access to your bank account.

"Treat them like cash and don't get them automatically refilled because when you do that you create another layer between you and the bank which makes it harder to detect fraud and makes the risk greater," said Gill.

No one wants to be a victim but anytime you use a mobile app to do business you are vulnerable, so stay on top of your bank and check your account often.