Some versions of Sonos One (1st and 2nd generation) allow partial or full memory access via attacker controlled hardware that can be attached to the Mini-PCI Express slot on the motherboard that hosts the WiFi card on the device.
A serial interface can be accessed with physical access to the PCB of Wattsense Bridge devices. After connecting to the interface, access to the bootloader is possible, as well as a Linux login prompt. The bootloader access can be used to gain a root shell on the device. This issue is fixed in recent firmware versions BSP >= 6.4.1.