Interesting story linked below, a group has checked over 1200 Android phones from all makes, including google and Samsung and Sony, and has found them to be missing parts of security patches the manufactures say they got.
So if google released a security patch version XXXX and Samsung releases it for their phones, those patches are actually missing some of the security updates that google originally released in those patches, the manufacture did not include them in their devices update, so you think you may have a security hole patches because your running version XXXX, when in fact your device did not get that particular patch.
Have a read, it seems to affect the lesser known brands more but they did note Samsung and Sony devices missing the odd patch, they have a tool you can use to scan your phone to check if your missing any patches in the security updates:
http://www.theverge.com/2018/4/12/17228510/android-phone-manufacturers-missed-security-updates-lie
So if google released a security patch version XXXX and Samsung releases it for their phones, those patches are actually missing some of the security updates that google originally released in those patches, the manufacture did not include them in their devices update, so you think you may have a security hole patches because your running version XXXX, when in fact your device did not get that particular patch.
Have a read, it seems to affect the lesser known brands more but they did note Samsung and Sony devices missing the odd patch, they have a tool you can use to scan your phone to check if your missing any patches in the security updates:
http://www.theverge.com/2018/4/12/17228510/android-phone-manufacturers-missed-security-updates-lie