They found a vulnerability
Netgear has urged users to update the firmware for a number of its routers as soon as possible.
This includes the Wireless AC Nighthawk, Wireless AX Nighthawk (WiFi 6) and Wireless AC models, in which a vulnerability was discovered. The company does not disclose details, although it notes that the vulnerability concerns a buffer overflow before authentication.
The Netgear website has a list of all affected routers and the latest firmware for them.