Warning! Nexus S 4G susceptible to same USSD exploit as galaxy s3, even with cyanogenmod

Yes but they are stating that it doesn't apply to Nexus/AOSP users... So I wouldn't get to excited over this just yet...

I wouldn't let your guard down but I wouldn't loose sleep over this just yet.
 
If the dialer shows *#60# or nothing at all, then the exploit does not work on your phone. Like the article says, this should only work on Samsung phones with Touchwiz. If you are on the stock ROM, or an AOSP ROM, it should not work.

If the exploit works with your custom ROM, like CM, then it is a problem with the ROM, not the Nexus S.