Over the weekend, members of the OnePlus community reported cases of unknown credit card transactions occurring on their credit cards post purchase from oneplus.net. We immediately began to investigate as a matter of urgency, and will keep you updated.
As a precaution, we are temporarily disabling credit card payments at oneplus.net. PayPal is still available, and we are exploring alternative secure payment options with our service providers.

Source: An Update on Credit Card Security – OnePlus Forums

With the camera problems and data being sent quietly to a Chinese server, OnePlus is not exactly inspiring confidence, which is a shame after such succesful and valuable launch products in the Android space