US mother and her two daughters logged on to Facebook from mobile phones last weekend and wound up in a startling place: strangers' accounts with full access to tons of private information.

The glitch the result of a routing problem at the family's wireless carrier, US telco giant AT&T - revealed a little known security flaw with far reaching implications for everyone on the internet, not just Facebook users.

In each case, the internet lost track of who was who, putting the women into the wrong accounts. It doesn't appear the users could have done anything to stop it. Several security experts said they had not heard of a case like this, in which the wrong person was shown a web page whose user name and password had been entered by someone else.