October’s macOS security update contained a fix for a vulnerability that Trend Micro privately disclosed to Apple earlier this year. The vulnerability (designated as CVE-2017-13811), was in the fsck_msdos system tool. This tool checks for and fixes errors in devices formatted with the FAT filesystem, and is automatically invoked by macOS when a device using FAT (such as a USB disk or an SD card) is inserted.
Post from: Trendlabs Security Intelligence Blog - by Trend Micro
October macOS Patch Fixes FAT/USB Vulnerability