Adobe have acknowledged a new zero day exploit for the Flash and PDF platforms. They will release a new version shortly for Adobe Reader and Flash Player - Adobe Reader X will not get an update, until the quaterly patch cycle, as its sandbox technology mitigates the problem.

There is an active exploit out there (a Flash object), which is currently buried in an Excel worksheet inside an e-mail. The exploit works on Windows, OS X, Linux and UNIX platforms, with Flash installed. Look out for PDFs to also be added to the list.

There's something I somehow hadn't considered before - how Flash could undermine Apple's security

I think it's fair to say Apple have already considered it though

Not sure where he heard it, but one of my nephew's favourite lines is, 'It's not a problem, it's a disaster!'

This is not a problem on the iPad and iPhone.