CSI:Cyber (S01E09) was about "JuiceJacking" where plugging your smartphone into a public USB charging station MAY allow your smartphone data to be stolen (see 3-minute clip below).
Best defense against JuiceJacking is to carry your own AC adapter...
...and not trust any public USB-only charging ports.
Security researcher Brian Krebs wrote a column on this...
... in August 2011. At the time, iPhones/iPads/iPod Touch were vulnerable to JuiceJacking (up to and including iOS v6). As of iOS v7, Apple added a "Trust this Computer"...
...query when plugging into an unknown USB data port -- answer "Don't Trust" or "NO" if it's not your computer; your iDevice battery will still recharge).
So, an up to date iPhone is protected. Not sure about your Android / Windows Phone / Blackberry ? Bring your own AC charger as public AC outlets with your adapter are OK.
More up to date info from a Google search of "JuiceJacking":