Can a bluetooth speaker contain malware? If someone were to find a random bluetooth speaker laying around and tries to connect with it, is there a possibility that the speaker has malware in it?
It is technically possible, because a Bluetooth device will likely contain firmware and a small CPU (so it's not just a dumb variable resistor and speaker driver). In a purely theoretical sense, it would be possible for malware in such a device to spread by exploiting a bug in the Bluetooth protocol to gain code execution or unauthorized access to another Bluetooth-capable device. However, the chances of this are so slim as to be utterly negligible. There are better ways to infect someone. You can safely disregard a Bluetooth speaker as a malware infection vector.
Regardless, it is not a bright idea to connect to something random you see lying around.