As expected, the January 2020 security patch for Android has started to arrive for Pixel 2 and newer Pixel phones. Pixel 4 users will be getting the update at the same time as the older Pixels, while the first-generation Pixel will no longer receive updates. Those who didn't get the December patch will get a cumulative January update.
It brings the usual fixes and patches for vulnerabilities that range from "high" to "critical." One of the significant repairs was for a media framework issue that an attacker could exploit by executing arbitrary code through a crafted file. If you want to check out the update yourself, factory and over-the-air (OTA) images are available through the Android Developers website.
Source: 9to5Google