There are some possible attacks using combinations of malware in the host computer, "human engineering", hidden cameras, theft, replacement of the device, infiltration of Satoshilabs, etc.. Appears to be safe if the latter two are considered unlikely and the device is used strictly according to the instructions.
REALLY?
ho god , i boght trezor to fel safe, not to feel into troubles
holy fk
so i can loose my btc if someone hack the trezor labs?
If someone gets a malicious version of the firmware, signed with the authentication keys held by Satoshilabs managers, it may then convince users to download and install that "firmware update" in their Trezor. That malicious firmware then could steal the coins, in many ways. As long as Satoshilabs takes good care of those keys, that risk does not exist.
A thief may substitute a malicious fake Trezor for the real one, when the user buys it. A fake Trezor too could steal the keys in many ways. As long as Satoshilabs keeps close watch on their shipping dept, and users only buy Trezors directly from them, that risk should be small.
The thief could also convince a user to download and install a non-authenticated version of the firmware. That would cause the Trezor to wipe its memory clean and display a warning on its window. The thief then would have to convince the user to ignore that warning, and re-enter the 24 magic words, from which the private blockchain keys are derived. Users should be wary of re-entering the magic words after such a warning.
(Many years ago some pranksters would dial a random fixed phone number, pretended to be the phone company, and asked the person to drop the set into a bucket of water, "for a test". Many users did.)