After a Samsung Galaxy S10 owner in Britain reported this week that the fingerprint sensor on her phone could be fooled simply by adding a screen protector to the phone, Samsung has acknowledged the issue and promised to fix it with an upcoming software update.

The Galaxy S10 is Samsung’s first smartphone to feature an ultrasonic, in-display fingerprint sensor that uses sound waves to detect fingerprint shapes.
Apparently all it takes to fool the sensor is a cheap screen protector which seems to allow anyone to unlock the phone by placing a finger in the appropriate space.
The issue seems to affect plastic or silicon screen protectors, so for now Samsung is recommending folks who are currently using a third-party screen protector either remove it and erase any currently saved fingerprints, or disable fingerprint recognition until a software patch is available — which could possibly be as soon as next week.
The Galaxy S10 also has a face unlock feature, or you could just resort to using a pattern, pin, or password.
Incidentally, the Google Pixel 4 and Pixel 4 XL announced this week don’t even have fingerprint sensors — just a fancy new face unlock feature that’s apparently of limited use until third-party app developers add support.
via /r/Android, Reuters, and BBC