They found a vulnerability
Netgear has urged users to update the firmware for a number of its routers as soon as possible.
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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.