{"schemaVersion":3,"id":"CVE-2020-12667","aliases":["UBUNTU-CVE-2020-12667","DEBIAN-CVE-2020-12667"],"status":"published","duplicateOf":null,"title":null,"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.","dates":{"published":"2020-05-19T00:00:00.000Z","modified":"2024-08-04T12:04:22.538Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.5,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":10,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":10,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":5,"severity":"medium","vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.02612,"percentile":0.85189,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":-0.007000000000000062,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.02619},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.02612,"percentile":0.85189}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.02619,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.02548,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.02612,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.02612,"percentile":0.85189}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-400","name":"Uncontrolled Resource Consumption","description":"The product does not properly control the allocation and maintenance of a limited resource.","type":"weakness","status":"Draft","abstraction":"Class","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/400.html"}],"affected":[{"vendor":"debian","product":"knot-resolver","name":"knot-resolver","label":"knot-resolver","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/knot-resolver","purlType":"deb","versions":[{"text":"< 5.1.1-0.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 5.1.1-0.1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"knot-resolver","name":"knot-resolver","label":"knot-resolver","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/knot-resolver","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null},{"text":"< 3.2.1-3ubuntu2.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"All versions (No fix recorded) | < 3.2.1-3ubuntu2.2","eol":null,"hubHref":null},{"vendor":"nic","product":"knot_resolver","name":"knot resolver","label":"knot_resolver","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"< 5.1.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 5.1.1","eol":null,"hubHref":"/vendor/nic/knot_resolver"}],"affectedCount":3,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/","label":"en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/","hostname":"en.blog.nic.cz","tags":["REPORT","Technical Description","Vendor Advisory"]},{"url":"https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html","label":"www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html","hostname":"www.knot-resolver.cz","tags":["REPORT","Release Notes","Vendor Advisory"]},{"url":"http://www.openwall.com/lists/oss-security/2020/05/19/2","label":"www.openwall.com/lists/oss-security/2020/05/19/2","hostname":"www.openwall.com","tags":["Mailing List","REPORT","Third Party Advisory"]},{"url":"http://cyber-security-group.cs.tau.ac.il/#","label":"cyber-security-group.cs.tau.ac.il","hostname":"cyber-security-group.cs.tau.ac.il","tags":["REPORT","Technical Description","Third Party Advisory"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/","label":"lists.fedoraproject.org/archives/…","hostname":"lists.fedoraproject.org","tags":["Vendor Advisory"]},{"url":"https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html","label":"lists.debian.org/debian-lts-announce/2024/04/msg00017.html","hostname":"lists.debian.org","tags":["Mailing List"]},{"url":"https://ubuntu.com/security/CVE-2020-12667","label":"ubuntu.com/security/CVE-2020-12667","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2020-12667","label":"www.cve.org/CVERecord?id=CVE-2020-12667","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-7047-1","label":"ubuntu.com/security/notices/USN-7047-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2020-12667","label":"security-tracker.debian.org/tracker/CVE-2020-12667","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["DLA-3795-1","USN-7047-1"],"duplicates":[],"related":["USN-7047-1"]},"timeline":[{"kind":"published","date":"2020-05-19T00:00:00.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-08-04T12:04:22.538Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":31,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T16:02:11.232Z","stale":false,"partial":false}}