{"id":"CVE-2021-3128","aliases":["EUVD-2021-26477","GHSA-289v-jmv7-6xmx"],"status":"published","title":"In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware \u003c 3.0.0.4.386...","description":"In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware \u003c 3.0.0.4.386.42095 or \u003c 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.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.16191,"percentile":0.96961,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-834"],"published":"2021-04-12T17:41:07Z","modified":"2026-06-17T04:04:42Z","products":[{"vendor":"asus","product":"rt-ac1750_b1_firmware"},{"vendor":"asus","product":"rt-ac1900_firmware"},{"vendor":"asus","product":"rt-ac1900p_firmware"},{"vendor":"asus","product":"rt-ac1900u_firmware"},{"vendor":"asus","product":"rt-ac2900_firmware"},{"vendor":"asus","product":"rt-ac3100_firmware"},{"vendor":"asus","product":"rt-ac5300_firmware"},{"vendor":"asus","product":"rt-ac58u_firmware"},{"vendor":"asus","product":"rt-ac65u_firmware"},{"vendor":"asus","product":"rt-ac66u_b1_firmware"},{"vendor":"asus","product":"rt-ac68p_firmware"},{"vendor":"asus","product":"rt-ac68r_firmware"},{"vendor":"asus","product":"rt-ac68rw_firmware"},{"vendor":"asus","product":"rt-ac68u_firmware"},{"vendor":"asus","product":"rt-ac68w_firmware"},{"vendor":"asus","product":"rt-ac85u_firmware"},{"vendor":"asus","product":"rt-ac86u_firmware"},{"vendor":"asus","product":"rt-ac88u_firmware"},{"vendor":"asus","product":"rt-ax3000_firmware"},{"vendor":"asus","product":"rt-ax55_firmware"},{"vendor":"asus","product":"rt-ax56u_firmware"},{"vendor":"asus","product":"rt-ax58u_firmware"},{"vendor":"asus","product":"rt-ax68u_firmware"},{"vendor":"asus","product":"rt-ax82u_firmware"},{"vendor":"asus","product":"rt-ax86u_firmware"},{"vendor":"asus","product":"rt-ax88u_firmware"},{"vendor":"asus","product":"zenwifi_ax_\\(xt8\\)_firmware"}],"references":[{"url":"https://www.asus.com/Networking-IoT-Servers/WiFi-6/All-series/RT-AX3000/HelpDesk_BIOS/","tags":["x_refsource_MISC","x_transferred","Product","Vendor 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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.","status":"published","published":"2021-04-12T17:41:07Z","modified":"2024-08-03T16:45:51.264Z","updated_at":"2026-11-02T14:33:04.020035Z"}],"euvd":[{"id":"EUVD-2021-26477","description":"In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware \u003c 3.0.0.4.386.42095 or \u003c 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.","status":"published","published":"2021-04-12T17:41:07Z","modified":"2024-08-03T16:45:51Z","updated_at":"2026-11-03T03:25:13.531128Z"}],"ghsa":[{"id":"GHSA-289v-jmv7-6xmx","title":"In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware \u003c 3.0.0.4.386...","description":"In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware \u003c 3.0.0.4.386.42095 or \u003c 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.","status":"published","published":"2022-05-24T17:47:10Z","modified":"2023-01-29T05:06:21Z","cwes":["CWE-834"],"updated_at":"2026-11-02T14:46:00.036476Z"}],"nvd":[{"id":"CVE-2021-3128","description":"In ASUS RT-AX3000, ZenWiFi AX (XT8), RT-AX88U, and other ASUS routers with firmware \u003c 3.0.0.4.386.42095 or \u003c 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.","status":"published","published":"2021-04-12T19:15:14.83Z","modified":"2026-06-17T04:04:42.857Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-834"],"updated_at":"2026-11-02T14:06:51.610648Z"}]}}