I just checked my three devices using their serial numbers from the link in the start of the thread. My 710 says it's impacted, and TT are working to see if they can produce an update for it. My 720 says it can have an update, and a link is provided. My 300, the oldest of the devices I have, says "all is fine, nothing to worry about".
I am waiting to see what happens tomorrow. Strangely I just powered the 720 up for the first time in a few days and it popped up a message saying "There is probably a free map update available, please check TomTom Home". I don't recall it ever saying that before.