WhatsApp Web, but unfortunately it needs some improvements in its web version. An independent 17-year-old security researcher Indrajeet Bhuyan reported two security holes in the WhatsApp web client that in some way exposes its users’ privacy. The new version of WhatsApp Web allows us to view a user’s profile image even if we are not on the contact list of that user. Even if the user has set the profile image privacy setting to “Contacts Only,” the profile picture can be viewed by out of contacts people as well.
Source: https://thehackernews.com/2015/01/whatsapp-web-mobile-app.html