Except if you find an XSS vulnerability in a site, you already have a serious security vulnerability that can be abused in many different ways to compromise a user. pushState simply makes one of those ways (phishing) more effective.
Personally, I'd rather take actions that don't require user interaction, like stealing the user's session cookie silently in the background or making other requests on their behalf to the website. That can be done via an invisible iframe on an otherwise legitimate website (which, I suppose, you could also consider to be "dangerous").
Comments
Except if you find an XSS vulnerability in a site, you already have a serious security vulnerability that can be abused in many different ways to compromise a user. pushState simply makes one of those ways (phishing) more effective.
Personally, I'd rather take actions that don't require user interaction, like stealing the user's session cookie silently in the background or making other requests on their behalf to the website. That can be done via an invisible iframe on an otherwise legitimate website (which, I suppose, you could also consider to be "dangerous").