2006 Pontiac Grand Prix Engine light and leaking

I moved my car this morning and found the engine light was on. The engine sounded as though it was running much lower, and then I discovered what appears to be leaking on the road. This leak appears to be coming along the muffler line. Prior to this, my computer was warning to check my gas cap - upon inspection, it seemed to be attached fine.

I am wondering if this is a major repair or an less expensive repair.