Router manufacturer D-Link admitted that some of its routers have a vulnerability that could allow hackers access to a device's administrative settings, but it has issued patches.

According to a blog post from SourceSec Security Research, some D-Link routers have an insecure implementation of the Home Network Administration Protocol (HNAP), which could allow an unauthorised person to change a router's settings.

SourceSec published a proof-of-concept software tool called HNAP0wn that would enable the hack, a move that D-Link criticised. "By publicising their tool and giving specific instructions, the authors of the report have publicly outlined how the security can be breached, which could have had serious repercussions for our customers," D-Link said in a statement.

D-Link said it only appeared possible to hack the routers using the software tool and not just with standalone code.

D-Link and SourceSec differed over which models were vulnerable. SourceSec wrote that it suspected that all D-Link routers made since 2006 with HNAP support were affected, but they said they had not tested all of them.

D-Link said the models affected are the DIR-855 (version A2), DIR-655 (versions A1 to A4) and DIR-635 (version B). Three discontinued models, DIR-615 (versions B1, B2 and B3), DIR-635 (version A) and DI-634M (version B1), are also affected.

The company said new firmware updates are being made available across its websites.