This answer covers a non-data-security risk that may also be worth considering:
Worst case" for a system with ANY hardware port - total internal destruction in seconds.
"USB killers" have been mentioned - and have been dismissed by a number of people as being no different to other physical destructive attacks.
This comparison is incorrect.
A "USB killer" is a (usually) USB memory stick sized device that plugs into a USB port
(or other port if so designed) and delivers a high energy and/or high voltage impulse into the port with the designed aim of destroying as much of the system as possible.
While USB killers are offered or promoted by some sources as ESD testing devices and to demonstrate whether the USB ports exhibit "ESD vulnerability" (some test) this is unlikely to be the reason that the cool-kid plugs one into your computer while you are absent. It is suggested by some sites that proper design will avoid damage from such devices. I have a Masters in Electrical engineering and 50 years experience. Should I wish (which I certainly don't) I could produce a device that would defeat all but systems expressly designed to protect against exceptional high energy high voltage attack. Opto or other couplers, isolation, high energy capable clamps, ... .
These devices really exist.
They are easy to build and trivially easy to use. They are often designed to charge from the USB port BUT can be precharged. A device using eg "super capacitors" can deliver an impulse in a very small fraction of a second that has enough energy to do substantial damage to much of the system.
If someone was keen enough (and a few may be) a wired capacitor bank could be used to deliver far more energy. Wire can run down a sleeve and across the palm of the hand to the "head". A device with minimal risk to the user could easily be produced.
There ARE people who think it is 'cool' to use these sorts of devices.
Also people who would perhaps like to do damage to your property using axe-attack, incineration, defenstration, Shotgun, Desert-Eagle or other "suitable means".
HOWEVER, of all these* the USB killer attack is (usually) silent, rapid, inobvious and fatal. It MAY be able to be implemented entirely covertly in seconds. ->
Sit at table opposite or near laptop.
Slide hand with USB killer in into nearest USB port.
Cycle.
Leave.
The device could be precharged - making killing time somewhere under a second from insertion to removal.
*The Desert Eagle or Shotgun is liable to be rapid and fatal.
Silence is not a known feature of either.