VULNERABILITY
be a sitting duck
to be vulnerable to attack, physical or verbal.You are a sitting duck out there. Get in here where the enemy cannot fire at you.The senator was a sitting duck because of his position on school reform.
have a glass jaw
to be susceptible to collapsing when struck on the head. (Informal. Said only of boxers who are frequently knocked down by a blow to the head.)When the prizefighter was knocked out in his third fight, the newspapers said he had a glass jaw.Once a fighter has a glass jaw, he's finished as a boxer.
sitting target
someone or something that is in a position that is easily attacked.The old man was a sitting target for the burglars. He lived alone and did not have a telephone.People recently hired will be sitting targets if the company needs to cut back.