[lmontrieux]

Oh, what a fantastic idea. Just take an old smartphone that the manufacturer stopped shipping security updates for ages ago (if they ever did it at all), and get it to record what goes on inside your home. What could possibly go wrong?

You might want to look at http://androidvulnerabilities.org/ to see the sorry state of security on Android phones. The older they get, of course, the worse it is.

[userbinator]

All I see are tons of local privilege escalation, which is concerning if you like to download and run random not-very-trustworthy apps, but it's actually not of much significance if all you're using the phone for is as a network camera. IMHO these are the good exploits, since they let you get root and have full control over the device so you can repurpose it more easily for other things... like network cameras.

Remote exploits that require no user action are the only thing to worry about here, and Stagefright is AFAIK the only one I've heard about so far (simple solution: take the SIM card out - what do you need it for in this application anyway?)