{"id":"UBUNTU-CVE-2026-19401","details":"Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.","modified":"2026-09-10T11:01:19.154491259Z","published":"2026-08-26T09:16:00Z","upstream":["CVE-2026-19401"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-19401"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-19401"}],"affected":[{"package":{"name":"nsd","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.2-1","4.1.6-1","4.1.7-1","4.1.7-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.1.7-1ubuntu0.1~esm1","binary_name":"nsd"},{"binary_name":"nsd3","binary_version":"4.1.7-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"}},{"package":{"name":"nsd","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.16-1build1","4.1.17-1","4.1.17-1build1","4.1.17-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"nsd","binary_version":"4.1.17-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"}},{"package":{"name":"nsd","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.26-1","4.1.26-1build1","4.1.26-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"nsd","binary_version":"4.1.26-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"}},{"package":{"name":"nsd","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.3.5-1","4.3.7-1","4.3.8-1","4.3.8-1build1","4.3.9-1","4.3.9-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.3.9-1ubuntu0.1~esm1","binary_name":"nsd"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"}},{"package":{"name":"nsd","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.7.0-1","4.8.0-1","4.8.0-1build1","4.8.0-1build3","4.8.0-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"nsd","binary_version":"4.8.0-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"}},{"package":{"name":"nsd","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.12.0-1","4.13.0-6","4.14.0-1","4.14.0-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"nsd","binary_version":"4.14.0-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"},{"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"}]}