Comments from the mothership:
In a statement to Engadget, Apple claimed that "the vast majority of OS X users are not at risk...With OS X, systems are safe by default and not exposed to remote exploits of bash unless users configure advanced Unix services."
From:
Apple Claims 'Vast Majority of OS X Users' Safe from Bash/Shellshock Exploit | Mac|Life
Cult of Mac also provided a handy method of checking to see if your OS X unit is at risk. Simply open your terminal, and copy and paste the following command into the interface:
env x=’() { :;}; echo vulnerable’ bash -c ‘echo hello’
If you're not at risk, the Terminal should reply with:
bash: warning: x: ignoring function definition attempt bash: error importing function definition for `x’ hello
I don't recommend this if you are unfamiliar with Terminal. I can tell you my iMac running 10.9.1 replied as above.