The passwords for at least 500,000 wifi routers in the Netherlands can still easily be discovered by hackers, even though the problem has been known since the end of 2011, according to the consumers association Consumentenbond.
The organisation says specific types of routers from KPN, UPC and Ziggo are still open to abuse and the companies are now trying to find a solution. The telecoms watchdog Opta has also been informed.
The problem centres on KPN (Experia ZTE H220N), Ziggo (Ubee evw3200) and Horizon mediabox from UPC. Other routers affected include the Linksys E1000 and E2000.
Hackers do have to be close to the wifi system in order to break in, the Consumentenbond said.
Consumers should get in touch with their internet service provider to find out if they are at risk and how to make their system safer, the consumer lobby group said.