We are yet to see the security update for the month of March arrive from Google, but considering the roll out is on its way, the company has made the update's factory images available. The new factory images are there for devices such as Nexus 5 (model MMB29V), Nexus 5X ( models MMB29V and MHC19J), Pixel C model number MXC15G, Nexus Player (model MMB29V), Nexus 7 (2013, MMB29V), Nexus 9 (model MMB29V) and Nexus 10 (LMY49H) variant. Nothing has been revealed about the Nexus 6P as of yet, nevertheless, the Nexus 6 (MMB29V) model is also on the list.
The security update for March will address several familiar vulnerabilities, such as a critical security vulnerability that would likely allow remote access for code execution using different methods including MMS, email and browsing the web when then a media file would be processed by the device. Though there have been no reports about this vulnerability being used to attack users, it is comforting to know that it will get a much needed patch. Over the Air updates of the March security patch will come shortly after.
If you are interested in flashing these images onto your Nexus handset then you can access all the vital software files and their download instructions directly from here. If you'd like to get the detailed information on this security update then check out the Android blog
for the official release statement from Google.