I tackled fixing an exhaust leak on my daughters 2010 Maxima yesterday. I have been hearing the leak especially on cold starts but it has continually gotten worse. It had gotten so bad that I could smell exhaust fumes when sitting in traffic.
What I found when I took off the converter was really shocking. I was suprised to find that the upper flange was not even welded to the converter. I mean there was a weld there, but the weld did not penetrate the flange at all. I will try to post a picture of the weld.
I am sure that if mine is like this then there are many more out there with this same issue. This is an expensive repair if you have to take it to a shop. This in my opinion is a factory defect that could case someone to die from carbin monoxide poisoning.

If your car has an exhaust leak then this may be your problem. This is on the left side of the engine (next to firewall).
Thanks

Wow. initially, when I looked at it, I thought, "That's a spinning / floating flange, it's supposed to look like that."

Nope. You nailed it. That's a terrible welding job!

Now the problem is, it's full of corrosion, so welding it now will be a huge challenge.

The rust on the flange was not problem for my grinder

Good deal - Well-handled!