Computer security is quite broad, so it depends what you're after. I can tell you what languages were involved when I took a security course at UNSW. It included x86 assembly, C, SQL, and Java. Assembly for reverse engineering, C for exploitable memory bugs, SQL for injection attacks, and Java for sloppy development in general.
Knowing your way around Unix based OSes, and understanding how common network protocols function (particularly HTTP) helps too.
But don't focus on the languages so much, it's about the security concepts in general. You'll pick up the languages as you gain experience.
"We are a way for the cosmos to know itself." - Carl Sagan
"I do not fear death. I had been dead for billions and billions of years before I was born, and had not suffered the slightest inconvenience from it." - Mark Twain
An open mind is willing to consider new ideas, while provisionally accepting those backed by empirical evidence, and provisionally rejecting those without.