EE is to release an emergency upgrade for its Brightbox 1 and 2 routers after a security flaw was identified by a researcher.
Scott Helme drew attention to a vulnerability which made remote access to EE's broadband routers possible.
According to EE, the threat to end-users is "moderate". As such, the company is to send out an automatic upgrade by the end of January.
Speaking to the BBC, a spokesperson for EE said anyone who has signed up for EE's home broadband service since early 2012 is affected.
The news provider estimates that around 350,000 broadband subscribers will need an upgrade for their router.
EE said it treats all security matters "seriously".
"While no personal data will be compromised by the device itself, we would like to reassure customers that we are working on a service update which we plan to issue shortly," the firm stated.
The company advised that home broadband customers, regardless of their service provider, should only give network access to people they trust.
"Customers should also be suspicious of any unsolicited emails and web pages, and keep their security software up to date," EE added.