Simon Rockman reports:
A Windows 10 feature, Wi-Fi Sense, smells like a significant security risk: it shares access to password-protected Wi-Fi networks with the user’s contacts. So giving a wireless password to one person grants access to everyone who knows them.
[…]
Wi-Fi Sense doesn’t reveal the password to your family, friends, acquaintances, and the chap at the takeaway who’s an Outlook.com contact, but it does allow them, if they are also running Wi-Fi Sense, to log in to your Wi-Fi. The password must be stored by Microsoft, and transferred to a device for it to work; Microsoft just tries to stop you looking at it.
Read more on The Register.