{"id":"UBUNTU-CVE-2021-3448","details":"A flaw was found in dnsmasq in versions before 2.85. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. This flaw makes a DNS Cache Poisoning attack much easier. The highest threat from this vulnerability is to data integrity.","modified":"2026-02-04T04:01:58.753735Z","published":"2021-04-08T23:15:00Z","related":["USN-4976-1","USN-4976-2"],"upstream":["CVE-2021-3448"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-3448"},{"type":"REPORT","url":"https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q1/014835.html"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-4976-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-4976-2"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-3448"}],"affected":[{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq@2.68-1ubuntu0.2+esm3?arch=source&distro=esm-infra-legacy/trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.66-4ubuntu1","2.67-1","2.68-1","2.68-1ubuntu0.1","2.68-1ubuntu0.2","2.68-1ubuntu0.2+esm1","2.68-1ubuntu0.2+esm2","2.68-1ubuntu0.2+esm3"],"ecosystem_specific":{"binaries":[{"binary_version":"2.68-1ubuntu0.2+esm3","binary_name":"dnsmasq"},{"binary_version":"2.68-1ubuntu0.2+esm3","binary_name":"dnsmasq-base"},{"binary_version":"2.68-1ubuntu0.2+esm3","binary_name":"dnsmasq-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-3448.json"}},{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq@2.79-1ubuntu0.16.04.1+esm1?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.79-1ubuntu0.16.04.1+esm1"}]}],"versions":["2.75-1","2.75-1ubuntu0.16.04.1","2.75-1ubuntu0.16.04.2","2.75-1ubuntu0.16.04.3","2.75-1ubuntu0.16.04.4","2.75-1ubuntu0.16.04.5","2.75-1ubuntu0.16.04.7","2.75-1ubuntu0.16.04.8","2.75-1ubuntu0.16.04.10","2.75-1ubuntu0.16.04.10+esm1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_version":"2.79-1ubuntu0.16.04.1+esm1","binary_name":"dnsmasq"},{"binary_version":"2.79-1ubuntu0.16.04.1+esm1","binary_name":"dnsmasq-base"},{"binary_version":"2.79-1ubuntu0.16.04.1+esm1","binary_name":"dnsmasq-base-lua"},{"binary_version":"2.79-1ubuntu0.16.04.1+esm1","binary_name":"dnsmasq-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-3448.json"}},{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq@2.79-1ubuntu0.4?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.79-1ubuntu0.4"}]}],"versions":["2.78-1","2.78-3","2.79-1","2.79-1ubuntu0.2","2.79-1ubuntu0.3"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"2.79-1ubuntu0.4","binary_name":"dnsmasq"},{"binary_version":"2.79-1ubuntu0.4","binary_name":"dnsmasq-base"},{"binary_version":"2.79-1ubuntu0.4","binary_name":"dnsmasq-base-lua"},{"binary_version":"2.79-1ubuntu0.4","binary_name":"dnsmasq-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-3448.json"}},{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq@2.80-1.1ubuntu1.4?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.80-1.1ubuntu1.4"}]}],"versions":["2.80-1ubuntu2","2.80-1ubuntu4","2.80-1.1ubuntu1","2.80-1.1ubuntu1.2","2.80-1.1ubuntu1.3"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"2.80-1.1ubuntu1.4","binary_name":"dnsmasq"},{"binary_version":"2.80-1.1ubuntu1.4","binary_name":"dnsmasq-base"},{"binary_version":"2.80-1.1ubuntu1.4","binary_name":"dnsmasq-base-lua"},{"binary_version":"2.80-1.1ubuntu1.4","binary_name":"dnsmasq-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-3448.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N"},{"type":"Ubuntu","score":"low"}]}