January security patches are live for the Nexus and Pixel devices, along with the January security bulletin which was just published today, January 2nd, on the official Android Source web page. For those that aren't keen on waiting for the security patches to hit their devices in the standard timely manner that Google usually sets up for its devices that are still supported, the images for the new software are always made available before Google begins pushing out the software to users over-the-air.
If you happen to be one of these types of users then it's possible to grab the new January security patch from either of the buttons below which will allow you install the new software using the Factory Images or the Full OTA Images, whichever you prefer. It should also be noted that there is no difference in the software based on the type of image you choose to flash to get the new security patch installed on your device, so users will be able to flash one or the other and get the same results. That said, the process of flashing system images to your device can easily damage things if the proper steps aren't followed, so if you aren't exactly sure how to complete the steps, it might be best to simply wait for Google to send out the software to you.
If you aren't sure how to complete the system image installation process, Google does provide a nifty and fairly easy-to-follow set of instructions to flash both the Factory Image and the Full OTA Image, so if every step is followed to the letter then you should have no issues. That said if you choose to do so then you are running the risk of doing something improperly that could render your device unusable. In regards to what security issues this patch fixes, it seems that it's mostly containing moderate risks, with a few high risks here and there. This is also just a simple security patch update compared to last month's patch which not only contained the security fixes for December, but also the Android 8.1 Oreo stable software which Google began pushing out to users on December 5th.