There is a new privacy feature on Viber for Android which lets you specify whether to show your Viber profile photo to everyone or just the users who are in your contact list. To hide your Viber photo from the users who are not in your contacts, do as follows:
1. Make sure the Viber on your Android device is updated to the latest version and open the app
2. Tap the 3line icon on to bottom right and go to the Settings.
3. Touch to open the Privacy option
4. Make sure to unmark the Show your photo option, so only your contacts can see your profile picture (Otherwise everyone who has your number, can see your picture)