Started to take apart the front clip of my car so I can detail it over winter, and I looked at the frame and saw a rust bubble. I poked it and behind is a 3/4'' hole in my frame! Its right above the front sway bar on the drivers side. Is this bad? How much would you say it would cost to fix?

Can't wait to see the answers on this one. I keep forgetting to check my frame and realistically, I'm not really sure what I'm looking for.
From what I've heard, cracks are what you're looking for.
Are the cracks more likely to happen on a rust frame?