Excessive Traffic Issue in ASUS Routers During IPv6 Operations

CVE-2021-3128

Summary

Certain ASUS routers, specifically models RT-AX3000, ZenWiFi AX (XT8), and RT-AX88U among others, face a routing loop issue when utilizing IPv6. This defect, which occurs in firmware versions prior to 3.0.0.4.386.42095 or 9.0.0.4.386.41994, can lead to an excessive flow of network traffic. The condition is triggered when an IP routing setup erroneously points to a point-to-point link. When the device receives a router advertisement with a global IPv6 prefix marked as on-link, it can result in a continuous loop of data packets, overwhelming the connection between the affected router and the Internet Service Provider's router.

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