Symbian Pre-existing condition
I suspect machines running Symbian may be immune to this particular problem. There was a similar problem to this one for the Symbian S60 system back in December last year, the so called S60 Curse of Silence. A specially crafted SMS would be sent to the phone and would occupy space in the mail box while not presenting itself in the message list. It soaked up space until the phone could no-longer receive SMS messages. I suspect Symbian was patched to handle that and this new 'sploit uses a similar technique.