CVE-2021-3128

high

Description

In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware < 3.0.0.4.386.42095 or < 9.0.0.4.386.41994, when IPv6 is used, a routing loop can occur that generates excessive network traffic between an affected device and its upstream ISP's router. This occurs when a link prefix route points to a point-to-point link, a destination IPv6 address belongs to the prefix and is not a local IPv6 address, and a router advertisement is received with at least one global unique IPv6 prefix for which the on-link flag is set.

References

https://www.asus.com/supportonly/RT-AC88U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC86U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC85U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC68W/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC68U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC68RW/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC68R/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC68P/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC65U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC58U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC5300/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC3100/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC2900/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC1900U/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC1900P/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC1900/HelpDesk_download/

https://www.asus.com/supportonly/RT-AC1750_B1/HelpDesk_download/

https://www.asus.com/Networking-IoT-Servers/WiFi-Routers/ASUS-WiFi-Routers/RT-AC66U-B1/HelpDesk_Download/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX88U/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX86U/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX82U/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX68U/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX58U/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX56U/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX55/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX3000/HelpDesk_BIOS/

https://www.asus.com/Networking-IoT-Servers/Whole-Home-Mesh-WiFi-System/ZenWiFi-WiFi-Systems/ASUS-ZenWiFi-AX-XT8-/HelpDesk_BIOS/

Details

Source: Mitre, NVD

Published: 2021-04-12

Updated: 2026-06-17

Risk Information

CVSS v2

Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

Severity: Medium

CVSS v3

Base Score: 7.5

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Severity: High

EPSS

EPSS: 0.02334