From the linked article (Mods, please delete if this is deemed to contravene copyright laws).
Again, we should stress that this is not necessarily a Canon-specific issue, as it is the Picture Transfer Protocol itself (rather than the cameras) that exhibits the security flaw. Photographers should remain vigilant and check for security updates from the manufacturers of their equipment.
I am not going to worry. While I do upload my images via the mini USB to my PC, it should be well protected so little chance of an attack. The only time I use the WiFi is between my iPad and the camera for remote control and not connected to the internet. If Canon do contact at some stage with a firmware update, I will install.
This supposed hack attack assumes you have connected your camera to a computer that does not have all the latest updates. Since most of us have fully patched updated computers and most of us use card readers this is a theory only hack so no worries for most of us. In reality hackers seek the most gain from the least amount of work so we are pretty safe as photographers.