With more than 70 million home networking devices in service, a zero-day for Linksys has a very wide reach. According to DefenseCode, an information security consultancy that’s just what turned up in a recent product evaluation for a client.

The company has not released full details of the root access vulnerability yet, but has posted a demonstration video (below) to YouTube:

In the video, DefenseCode researchers open the router’s shell (without authentication) and list the contents of files and directories.

According to Help-Net Security, it took DefenseCode just 12 days to develop the exploit. The company says it contacted Cisco, Linksys's owner, “months ago”.

The vulnerability affects all versions of Linksys firmware up to and including the current version, 4.30.14. DefenseCode intends to release a full description of the vulnerability within two weeks.

It’s an unwelcome development for Cisco, which in December began casting around for potential buyers for the consumer kit brand. ®

Update: Cisco has made the following statement to The Register: "Linksys takes the security of our products and customers’ home networks very seriously. Although we can confirm contact with DefenseCode, we have no new vulnerability information to share with customers – for our WRT54GL or other home routers. We will continue to review new information that comes to light and will provide customer updates as appropriate." ®