Many thanks (and to Lucius) for this information, I stand corrected! I remember I read this article a while back, but thought it was something that could be patched with a f/w update. According to the article, it isn't patchable, at least in the h/w versions affected, and I'm not sure whether or not it has been resolved in current versions. The vulnerability is in the STM32 chip they're using, so they need to change the chip, which isn't easy.

Taking this into account, one should definitely use a very strong passphrase (a.k.a. 25-th word) as well as a strong PIN. That's the way I've set up mine. This should give us enough time to take measures against theft.