A vulnerability has been detected in Android which can result in a compromise of your contact data. It works through your phone's automatic retrieval of MMS messages.
What you need to do:
On the
lookout blog there's a link to their Stagefright detector at the play store. Install it, run it, and it will tell you if your handset is vulnerable. If so, it offers links with help on how to turn off automatic MMS retrieval in Hangouts and the stock messaging app.
Here's the thing - there are conflicting reports on the extent and nature of the problem. On
this page it says that Google thinks it only affects devices up to and including Android 4.0 and that 90% of devices are "protected" - well I just checked my phone and the app tells me the handset is vulnerable (I'm on 4.2.2).
So I'm in the dark - if anyone has more info then by all means add it to the thread, but in the meantime, be cautious of MMS messages from unknown sources.