Edit: Only 2 of these were actually installed.

…these cameras contain a hardcoded list of Russian phone numbers, which can be used to open a backdoor. An SMS from one of these numbers can open shell and network access.

…the web management portal can be accessed, exposing live streams, by anyone with the camera IP.

Reports also suggest that pressure from the opposition political party in Slovakia led to the NBU investigations. The current government of the country, led by populist Robert Fico, initially denied reports that the cameras were of Russian origin and rebuffed any security concerns. Fico has what some would describe as a pro-Russia tilt, but you can read more about that elsewhere, if you are interested.