There's a risk of injury for just about any conditioning you could do whether it's running, crossfit, or basket weaving (you know the repetitive stress injury from that must be awful!). Do you worry about grievous injury just from lifting weights? Probably not. In my experience, when applied with a user listening to their body and using their brain, Crossfit isn't any more dangerous than normal weight lifting... same thing with running. Just stay smart and err on the side of easy. You don't have anyone to blame but yourself if you drink the Koolaid and injure yourself badly.
In your face, Space Coyote!