{"id":"CVE-2021-22161","aliases":["EUVD-2021-9307","GHSA-jw75-vvj8-5h3f"],"status":"published","title":"In OpenWrt 19.07.x before 19.07.7, when IPv6 is used, a routing loop can occur that generates...","description":"In OpenWrt 19.07.x before 19.07.7, 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. This affects the netifd and odhcp6c packages.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.00531,"percentile":0.45373,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-835"],"published":"2021-02-07T22:56:39Z","modified":"2026-06-17T03:36:43Z","products":[{"vendor":"openwrt","product":"openwrt"}],"references":[{"url":"https://openwrt.org/advisory/2021-02-02-1","tags":["x_refsource_CONFIRM","x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-22161"},{"url":"https://github.com/advisories/GHSA-jw75-vvj8-5h3f"}],"sources":{"cve":[{"id":"CVE-2021-22161","description":"In OpenWrt 19.07.x before 19.07.7, 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. This affects the netifd and odhcp6c packages.","status":"published","published":"2021-02-07T22:56:39Z","modified":"2024-08-03T18:37:17.772Z","updated_at":"2026-11-02T14:32:57.701381Z"}],"euvd":[{"id":"EUVD-2021-9307","description":"In OpenWrt 19.07.x before 19.07.7, 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. This affects the netifd and odhcp6c packages.","status":"published","published":"2021-02-07T22:56:39Z","modified":"2024-08-03T18:37:17Z","updated_at":"2026-11-03T03:25:03.638882Z"}],"ghsa":[{"id":"GHSA-jw75-vvj8-5h3f","title":"In OpenWrt 19.07.x before 19.07.7, when IPv6 is used, a routing loop can occur that generates...","description":"In OpenWrt 19.07.x before 19.07.7, 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. This affects the netifd and odhcp6c packages.","status":"published","published":"2022-05-24T17:41:18Z","modified":"2023-05-24T15:30:26Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:54:36.087743Z"}],"nvd":[{"id":"CVE-2021-22161","description":"In OpenWrt 19.07.x before 19.07.7, 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. This affects the netifd and odhcp6c packages.","status":"published","published":"2021-02-07T23:15:12.273Z","modified":"2026-06-17T03:36:43.53Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"},{"version":"2.0","score":3.3,"vector":"AV:A/AC:L/Au:N/C:N/I:N/A:P","level":"low","assessor":"primary"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:06:49.660551Z"}]}}