Am I affected?:
If you are using anything crypto-currency related, then maybe. As discovered by @maths22, the target seems to have been identified as copay related libraries. It only executes successfully when a matching package is in use (assumed to be copay at this point). If you are using a crypto-currency related library and if you see flatmap-stream@0.1.1 after running npm ls event-stream flatmap-stream, you are most likely affected. For example:

https://github.com/dominictarr/event-stream/issues/116