Due to Improper Access Control of NAND-based EFS in Snapdragon Automobile, Snapdragon Mobile and Snapdragon Wear, From fastboot on a NAND-based device, the EFS partition can be erased. Apps processor then has non-secure world full read/write access to the partition until the modem boots and configures the EFS partition addresses in its MPU partition.
In Android before 2018-01-05 on Qualcomm Snapdragon IoT, Snapdragon Mobile, Snapdragon Automobile APQ8096AU, MDM9206, MDM9650, MSM8996AU, SD 210/SD 212/SD 205, SD 425, SD 430, SD 625, SD 650/52, SD 820, SD 835, it is possible for the XBL loader to skip the authentication of device config.