Specifications are not clear, but the documentation says:
Ethernet Connection
[...] Note: To connect two or more computers to the Ethernet port, you will need a hub or broadband router (available at computer retailers).
[...] If you are connecting the Cable Modem directly to a computer, or to an Ethernet hub or broadband router with a cross-over switch, ask for Category 5e (CAT5e) straight-through cable. CAT5e cable is required for gigabit Ethernet (Gig-E), not regular CAT5 cable.
...and:
Making Ethernet Connections
- Connect one end of the yellow Ethernet cable to the yellow port on the back of the Cable Modem labeled “Ethernet 10/100/1000,” [...] and the other end to the Ethernet port on a computer, hub, or broadband router.
And as a switch is merely an intelligent hub, switches are supported too.
However, this implies the modem must have a built-in DHCP server and router, but it also seems it has no administrative user interface to configure those? Of course, things can work fine with default settings, but to be a bit more sure you could check the IP address of your computer, to see if it's in the private range. Seeing a private IP address is no 100% guarantee, but if it's not in the private range then your computer is connected to the internet directly. In that case a hub or switch is not good enough, and you'd need a router to give each computer its own local IP address.