In Soviet Russia, your SSL private key becomes public key. (the private key is held in memory by the nginx process. If you can dump memory, you can dump key)
(you may also want to generate a new key and get a new certificate if you use nginx, concurrent with patching this...)
You can't dump arbitrary memory with that bug. If you're very lucky and backend server already hacked or have holes, you can get some random part of previously send responce.
(you may also want to generate a new key and get a new certificate if you use nginx, concurrent with patching this...)