vulnerable

More or most likely to be exposed to the chance of being attacked or harmed, either physically or emotionally.

In my younger and more vulnerable years my father gave me some advice that I’ve been turning over in my mind ever since. ‘Whenever you feel like criticizing any one,’ he told me, ‘just remember that all the people in this world haven’t had the advantages that you’ve had.’

The elimination of [Roger] Federer after [Rafael] Nadal's loss to Lukas Rosol would have created mild panic among the fans of these gloriously gifted but now clearly vulnerable geniuses.

More or most likely to be exposed to the chance of being attacked or harmed, either physically or emotionally.

It's okay to get vulnerable every now and again.

More likely to be exposed to malicious programs or viruses.

a vulnerable PC with no antivirus software

at moderate risk of extinction though not quite endangered.

Welsh is merely a vulnerable language, but Irish and Scottish Gaelic are definitely endangered.