Moreover, these handset makers are allowed to include some of their own patches in the monthly updates. Since Google provides handset makers with these updates a month before they are released, these companies have enough time to include all the fixes they want for their phones.
Samsung is one of the companies that is pushing these security updates pretty often. In fact, the South Korean company releases monthly security updates and they're not exclusively pushed to flagships, as once in a while some of its newer mid-range devices are getting them too.
Today, Samsung announced the release of the December security update for its major flagship smartphones. The so-called Security Maintenance Release (SMR) includes patches from both Google and Samsung.
As Samsung explains in the announcement, Google's update includes patches up to Android Security Bulletin from December. Along with this, Samsung Mobile added 15 vulnerabilities and exposure items of its own.
These vulnerabilities are categorized by vulnerability: critical, high, moderate and low. This update doesn't contain any patches for critical or high vulnerabilities, just moderate and low.
Since Samsung mentioned that the December security update is aimed at its major flagship devices, we expect the Galaxy S7 and Galaxy S7 edge to be the first to receive it, but the Galaxy S6 and all its variations should follow soon.
The Galaxy Note 5 will surely get the update too, but other than these, it's unclear which other Samsung smartphones will receive the December security update.
Obviously, availability will vary by country and carriers, so don't despair if the update doesn't show up for you while in other countries is already available for download.