SECURITY ALERT: running MetaMask (and other wallets) can put you at risk of tracking and spoofing!
The folks over at Bloom have pointed out that running an in browser wallet extension like MetaMaskputs you at risk.
At the very least it lets sites know you are a cryptocurrency holder, at worst it lets other tabs potential pop up a fake transaction window and fool you.
Fixes may be on the way but for now their recommendation is just disable the extension whenever you are not using it. And my suggestion... Use an offline wallet to store your balance and only transfer to MetaMask etc. if and when you need to.
This of course is exactly the kind of issue that shows cryptocurrency is still just a disaster waiting to happen for many unskilled and incautious users.
You have been warned!