South Korea's KaKao Bank has told customers to switch off the fingerprint recognition option on Samsung Galaxy S10 phones because a security flaw lets unregistered prints unlock the handsets.
Samsung has acknowledged the problem and says it will soon issue a software patch to fix it.
The fingerprint sensor issue was uncovered by a British woman whose husband found he could unlock her phone using his thumbprint if he added a cheap screen protector to the device.
Digital-only bank KaKao has advised customers to switch to the phone's facial recognition option or a PIN when logging in to its service.