Posting this information received from NETGEAR.
We have released firmware updates (4.1.14, 5.3.11 and 4.2.27) for our legacy ReadyNAS devices which include patches for ShellShock. We strongly recommend updating affected devices to the latest firmware.
As best practice, it is recommended not to create static port forwards on your internet gateway device to your ReadyNAS. This will limit your exposure to any threats or vulnerabilities.
Our ReadyNAS OS6 devices are not exposed. Whilst they do contain the bash shell that is affected, the default shell is DASH, not BASH. DASH is the shell that would get executed from CGIs. BASH will be updated in a future release per standard practice.