o.k. I admit that I used a little bit of sensationalism in the title.
As demonstrated last week at the DEF CON Hacking conference (I would love to go to that!) it is highly recommended that you not share a charging cable with someone else. An excellent scenario is the first class area of a plane. There's a good chance that a corporate exec or two are flying first class and how easy would it be to offer your hacked charging cable to them being the "nice guy"!
Charging cubes, power adapters, etc. all are prime targets. Also those silly charging stations at the Metropolitan Art museum in NYC is another perfect example of targets.
This isn't a new problem and there are many solutions. such as
However, with all things its up to you and your risk appetite, My phone has wireless charging and lot of public places are supporting wireless charging now...
While I always stick to my own cables / chargers & carry a power-bank when on the move, I've assumed the phone's secure if password-protected & configured so that USB file transfer is disabled by default.
If I connect my phone --- an Mi6 --- to a PC's USB port, it defaults to the USB charging mode, and there's no access to storage in Windows Explorer.
You have to enable File Transfer from the phone if you want to transfer files, after which you'll have access.
(I've configured my phone with one password to unlock it & another to access the settings, so enabling File Transfer would require knowing both.)
Interestingly, this article says that when one of the DefCon attendees who claimed that File Transfer was off on his phone connected it to their 'kiosk' it immediately went into File Transfer mode!
Now I'm left wondering whether or not my phone's secure when it comes to juice-jacking via the USB port...