{"id":"CVE-2020-12667","aliases":["ALPINE-CVE-2020-12667","DEBIAN-CVE-2020-12667","DLA-3795-1","EUVD-2020-4965","GHSA-2gpj-6wgq-8636","UBUNTU-CVE-2020-12667","USN-7047-1"],"status":"published","title":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker...","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","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":"2026-11-12","score":0.02612,"percentile":0.85639,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400"],"published":"2020-05-19T00:00:00Z","modified":"2026-11-03T06:32:23Z","fixes":[{"ecosystem":"Alpine:v3.11","package":"knot-resolver","fixed_in":["4.3.0-r3"],"sources":["osv"]},{"ecosystem":"Alpine:v3.12","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.13","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.14","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.15","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.16","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.17","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.18","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.19","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.20","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.21","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.22","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.23","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"knot-resolver","fixed_in":["5.1.1-r0"],"sources":["osv"]},{"ecosystem":"Debian:12","package":"knot-resolver","fixed_in":["5.1.1-0.1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"knot-resolver","fixed_in":["5.1.1-0.1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"knot-resolver","fixed_in":["5.1.1-0.1"],"sources":["osv"]},{"ecosystem":"Ubuntu:20.04:LTS","package":"knot-resolver","fixed_in":["3.2.1-3ubuntu2.2"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Alpine:v3.11","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.3.0-r3"}]}]},{"source":"osv","ecosystem":"Alpine:v3.12","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.13","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.14","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.15","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.16","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.17","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.18","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.19","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.20","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.21","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.22","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-r0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-0.1"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-0.1"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1-0.1"}]}]},{"source":"osv","ecosystem":"Debian:10","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.1-3+deb10u2"}]}],"versions":["3.2.1-3","3.2.1-3+deb10u1"],"bundled":4},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0~beta2-123-g6134920-1","1.0.0~beta3-1","1.0.0~beta3-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.3-1","1.5.0-4","1.5.1-1","1.5.2-1","2.0.0-3","2.1.0-1","2.1.0-2","2.1.1-1","2.1.1-1ubuntu0.1~esm2"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.1-3ubuntu2.2"}]}],"versions":["3.2.1-3","3.2.1-3ubuntu1","3.2.1-3ubuntu2","3.2.1-3ubuntu2.1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.1-3ubuntu2.2"}]}],"versions":["3.2.1-3","3.2.1-3ubuntu1","3.2.1-3ubuntu2","3.2.1-3ubuntu2.1"],"bundled":4}],"products":[{"vendor":"nic","product":"knot_resolver"}],"references":[{"url":"https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/","tags":["x_transferred","Technical Description","Vendor Advisory","advisory","report"]},{"url":"https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html","tags":["x_transferred","Release Notes","Vendor Advisory","advisory","report"]},{"url":"http://www.openwall.com/lists/oss-security/2020/05/19/2","tags":["mailing-list","x_transferred","Mailing List","Third Party Advisory","advisory","report"]},{"url":"http://cyber-security-group.cs.tau.ac.il/#","tags":["x_transferred","Technical Description","Third Party Advisory","advisory","report"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/","tags":["vendor-advisory","x_transferred","web"]},{"url":"https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html","tags":["mailing-list","x_transferred","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-12667"},{"url":"http://www.nxnsattack.com"},{"url":"https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ"},{"url":"https://github.com/advisories/GHSA-2gpj-6wgq-8636"},{"url":"https://security.alpinelinux.org/vuln/CVE-2020-12667","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2020-12667","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2020-12667","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2020-12667","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-7047-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2019-10190","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2019-10191","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2019-19331","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2020-12667","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T00:00:00Z","modified":"2024-08-04T12:04:22.538Z","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":"adp"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:35:52.925152Z"}],"euvd":[{"id":"EUVD-2020-4965","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T00:00:00Z","modified":"2024-08-04T12:04:22Z","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"}],"updated_at":"2026-11-03T03:07:39.896975Z"}],"ghsa":[{"id":"GHSA-2gpj-6wgq-8636","title":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker...","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2022-05-24T17:18:08Z","modified":"2024-05-06T05:03:41Z","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"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:57:19.595262Z"}],"nvd":[{"id":"CVE-2020-12667","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T13:15:11.763Z","modified":"2026-06-17T02:52:06.19Z","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":"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":"secondary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:06:00.784809Z"}],"osv":[{"id":"ALPINE-CVE-2020-12667","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T13:15:11.763Z","modified":"2026-11-03T06:32:23.514627694Z","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"}],"updated_at":"2026-11-03T07:17:57.723967Z"},{"id":"CVE-2020-12667","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T13:15:11.763Z","modified":"2026-10-24T10:30:58.392503938Z","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"}],"updated_at":"2026-11-02T15:44:14.034736Z"},{"id":"DEBIAN-CVE-2020-12667","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T13:15:11.763Z","modified":"2026-10-26T12:00:29.440062667Z","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"}],"updated_at":"2026-11-02T15:45:32.862554Z"},{"id":"UBUNTU-CVE-2020-12667","description":"Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an \"NXNSAttack\" issue. This is triggered by random subdomains in the NSDNAME in NS records.","status":"published","published":"2020-05-19T13:15:00Z","modified":"2026-04-22T12:28:05.56678Z","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"},{"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"}],"updated_at":"2026-11-02T15:54:22.804634Z"},{"id":"DLA-3795-1","title":"knot-resolver - security update","status":"published","published":"2024-04-26T00:00:00Z","modified":"2026-03-09T01:18:07.178802Z","updated_at":"2026-11-02T15:46:12.203458Z"},{"id":"USN-7047-1","title":"knot-resolver vulnerabilities","description":"Vladimír Čunát discovered that Knot Resolver incorrectly handled input\nduring DNSSEC validation. A remote attacker could possibly use this issue\nto bypass certain validations. (CVE-2019-10190)\n\nVladimír Čunát discovered that Knot Resolver incorrectly handled input\nduring DNSSEC validation. A remote attacker could possibly use this issue\nto downgrade DNSSEC-secure domains to a DNSSEC-insecure state, resulting \nin a domain hijacking attack. (CVE-2019-10191)\n\nVladimír Čunát discovered that Knot Resolver incorrectly handled certain \nDNS replies with many resource records. An attacker could possibly use \nthis issue to consume system resources, resulting in a denial of service.\n(CVE-2019-19331)\n\nLior Shafir, Yehuda Afek, and Anat Bremler-Barr discovered that Knot\nResolver incorrectly handled certain queries. A remote attacker could \nuse this issue to perform an amplification attack directed at a target.\n(CVE-2020-12667)\n","status":"published","published":"2024-10-01T06:53:06Z","modified":"2026-04-27T17:47:13.764053897Z","updated_at":"2026-11-02T16:58:18.876384Z"}]}}