Fingerprint scanners are more-secure than passcode locks and other common security features, but are not completely secure. Fingerprint scanners can be circumvented by images of the owner's fingerprint, including photocopies and printouts of scanned images. Bypassing a fingerprint scanner this way requires access to the owner's fingerprint to create the image.
A less-common method of bypassing fingerprint scanners is to print 3D fingerprints on substances such as latex. These 3D prints can be worn over an individual's finger. Like using a scanned image or photocopy, this method requires access to the owner's fingerprint to make a copy.
Advanced fingerprint scanners that measure other biometric data are also vulnerable to these techniques. The hosts of "Mythbusters" demonstrate that it is possible to bypass scanners that measure body temperature, pulse and skin conductivity using photocopied fingerprint images.
Apple estimates that the odds of a partial fingerprint match working with its scanner are one in 50,000. Its estimate for the chances of correctly guessing a random passcode is one in 20,000, with the caveat that many people do not use random passcodes. Apple's hardware blocks access after failed attempts at a fingerprint match, making it unlikely that anyone could find a random partial match before losing access to the device.