Google introduced Android Pie at the beginning of August and with September already here, the monthly security update has just arrived. Unsurprisingly, the first phones receiving it are the Pixel devices, along with the Oreo-running Nexus 5X and Nexus 6P. The September 2018 Android Security update is OTA and brings minor patches and fixes to bugs. The full list of phones getting the patches is LG Nexus 5X and Huawei Nexus 6P from 2015, the Pixel and Pixel XL, as well as the Pixel 2 and Pixel 2 XL. The tablet Pixel C also joins them. It is worth mentioning the non-Pixel smartphones...
Source: https://www.gsmarena.com/september_security_patch_pixel_and_nexus_phones-news-33103.php