Smart gadgets are built to make life easier, but sometimes they create opportunities no one expected. Hackers have discovered that the smallest and strangest devices can open the door to big problems.

One of the most famous examples took place in a Las Vegas casino. Attackers slipped into the network through an internet-connected thermometer inside a decorative fish tank. From there, they accessed a database of high-roller information. The weakest point was not the casino’s servers, it was the aquarium in the lobby.

Everyday appliances have also been drafted into large cyberattacks. Security researchers have found smart fridges and light bulbs hijacked and turned into part of botnets, massive armies of connected devices that can flood websites with traffic. Even objects as ordinary as kitchen appliances can end up participating in internet battles.

And then there are the toys. A line of internet-connected teddy bears called CloudPets accidentally exposed more than two million recordings between children and parents. A toy meant to comfort kids turned into an unexpected privacy risk.

These examples show that almost anything with Wi-Fi can be mischievous. If a fish tank, a fridge, or even a teddy bear can be hacked, it is worth remembering that the convenience of “smart” often comes with hidden surprises.