innocent, wide-eyed, naVve, born yesterday, wet behind the ears.
2. susceptible to, unable to tolerate or withstand; subject to, given to, disposed to, likely to get, liable to; prone to, predisposed to, inclined toward, leaning toward.
3. open to attack, pregnable, penetrable, invadable, attackable, unresistant; precarious, risky, dangerous, hazardous, U.S. Inf. out on a limb.