{"id":"UBUNTU-CVE-2020-12667","details":"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.","modified":"2026-04-22T14:01:44.424833Z","published":"2020-05-19T13:15:00Z","related":["USN-7047-1"],"upstream":["CVE-2020-12667"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-12667"},{"type":"REPORT","url":"https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/"},{"type":"REPORT","url":"http://cyber-security-group.cs.tau.ac.il/#"},{"type":"REPORT","url":"http://www.openwall.com/lists/oss-security/2020/05/19/2"},{"type":"REPORT","url":"https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-12667"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-7047-1"}],"affected":[{"package":{"name":"knot-resolver","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/knot-resolver@1.0.0~beta3-1ubuntu0.1~esm1?arch=source&distro=esm-apps/xenial"},"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"],"ecosystem_specific":{"binaries":[{"binary_name":"knot-resolver","binary_version":"1.0.0~beta3-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-12667.json"}},{"package":{"name":"knot-resolver","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/knot-resolver@2.1.1-1ubuntu0.1~esm2?arch=source&distro=esm-apps/bionic"},"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"],"ecosystem_specific":{"binaries":[{"binary_name":"knot-resolver","binary_version":"2.1.1-1ubuntu0.1~esm2"},{"binary_name":"knot-resolver-module-http","binary_version":"2.1.1-1ubuntu0.1~esm2"},{"binary_name":"libkres6","binary_version":"2.1.1-1ubuntu0.1~esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-12667.json"}},{"package":{"name":"knot-resolver","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/knot-resolver@3.2.1-3ubuntu2.2?arch=source&distro=focal"},"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"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"knot-resolver","binary_version":"3.2.1-3ubuntu2.2"},{"binary_name":"knot-resolver-module-http","binary_version":"3.2.1-3ubuntu2.2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-12667.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}