Apple was hit by a class action lawsuit on Thursday that claims the company knew about a defect in the iPhone 5 line of smartphones that could result in high cell data usage.

The lawsuit, filed by consumer-rights law firm Hagens Berman, explains that the defect would occur when an iPhone 5 user "streamed high volumes of data for a period of 10-20 minutes." During this time, the hardware's GPU would take control of all video decompression, decoding and presentation, making the CPU unneeded. The CPU would then go to sleep in order to conserve its battery life, but the phone would then switch from streaming via Wi-Fi to LTE.

According to the firm's investigation, any iPhone 5 model running iOS 6 or iOS 7 was affected, and the problem was only addressed when Apple release iOS 8.1. However, prior to the updated OS, the Cupertino company only issued a fix for Verizon users shortly after the iPhone 5's launch in 2012, and even then, it only came after people started noticing and reporting the issue. AT&T users, meanwhile, received no such fix at the time nor did Apple acknowledge the problem.

"We believe Apple should not have withheld this repair for AT&T Wireless subscribers for any period of time," said Hagens Berman. "By withholding this information and repair, consumers were unaware of the defect and were left to sort out high cellular data charges with their wireless carriers."

The firm is now encouraging those affected by the defect to reach out to them in order to "find out more about your rights against Apple."