Doubtful, and ios7 (and 8) tightened up on pairing probably because of the scare of leaking data when charging with an untrusted USB peer. But maybe one of the first high-profile, mass-distributed ones?

Also, don't forget that jailbreaking itself by definition proves the possibility of attacking a non-jailbroken device via USB (or sometimes, even via the web in mobile safari). The fact that you get a visible Cydia app icon and optionally an SSH daemon with a known root password just means this time the attacker (hopefully, you) was benevolent.

> Doubtful, and ios7 (and 8) tightened up on pairing

They could still do more. It would be nice to be able to see a editable list of trusted devices. At the moment, on first connection, a "do you trust this computer?" prompt comes up. If you select "trust", to my knowledge there's no way to then revoke that trust. Additionally, there's no "don't ask me again" button, so if you do use your device with an un-trusted computer you have to be careful to never accidentally click the "trust" button every single time you plug it in (e.g. if you want to charge but don't want to sync).

You can revoke all pairing trusts (on ios8, at least) with:

  Settings > General > Reset > Reset Location & Privacy

AFAIK there is no UI for individual pairing management, but I think the full reset is completely safe/non-destructive otherwise -- just re-pair on the machines you do trust, and everything continues as usual without data loss or huge resync, etc.