Dozens of election systems intended to be isolated from the Internet have actually been continuously connected for long periods of time, according to a new report published by Vice on Thursday. The findings contradict longstanding claims by election officials and vendors about the security of voting systems.

The voting systems, reportedly produced by Omaha-based Election Systems & Software, have wireless internet capacities. But according to Vice, those are only intended to be active for short periods, either for testing or immediately after an election, when voting machines transmit preliminary vote totals to central tallying systems. Researchers, scouring the internet using parameters based on one known IP address of a fire-walled system in Rhode Island, found about 35 ES&S systems whose connections had been left open, in some cases for months or even years.

In an email to Fortune, ES&S denies its vote tabulators are ever connected to the Internet, and said its election management systems are secured, hardened, and not permitted online. “There is zero evidence any ES&S voting system has ever been compromised,” ES&S tells Fortune. “In some states it is a common practice to modem unofficial election results at the close of the polls to help the media in releasing early projections. This does not involve direct internet connectivity to the voting system.”

BY DAVID Z. MORRIS