Short answer no.
When you create a wallet with the chrome extension MM creates your new wallet. Unless someone is logging in from your computer with your password OR has the 12 word phrase then they'll be unable to get in.
But is the metamask still synced at the same time the users already logout or close the browser? because my metamask already sign in automatically, But i remember i was feel confusing to use it.
As long as the word phrase still secure. I believe nothing will be happening. But someone is able top stealing the data.
