Need help with spring poking out back of leather couch.

I just bought a used leather couch, and there is a spring poking out the back of the couch. It's not actually poking all the way through yet, there's just a small hole. I can push on it, and it goes in at least 6 inches or more. I can also feel that there is a vertical support right next to it. Maybe it's supposed to be attached to that support, and it came off? I know nothing about furniture repair, so any suggestions, or links you could give me would be very helpful.

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