{"id":"UBUNTU-CVE-2020-25684","details":"A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.","modified":"2026-05-26T20:00:40.772542295Z","published":"2021-01-19T00:00:00Z","related":["USN-4698-1"],"upstream":["CVE-2020-25684"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-25684"},{"type":"REPORT","url":"https://www.jsof-tech.com/disclosures/dnspooq/"},{"type":"REPORT","url":"http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q1/014599.html"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-4698-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-25684"}],"affected":[{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq?arch=source&distro=esm-infra-legacy%2Ftrusty"},"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","2.68-1ubuntu0.2+esm5","2.68-1ubuntu0.2+esm6"],"ecosystem_specific":{"binaries":[{"binary_version":"2.68-1ubuntu0.2+esm6","binary_name":"dnsmasq"},{"binary_name":"dnsmasq-base","binary_version":"2.68-1ubuntu0.2+esm6"},{"binary_name":"dnsmasq-utils","binary_version":"2.68-1ubuntu0.2+esm6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-25684.json"}},{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.75-1ubuntu0.16.04.7"}]}],"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"],"ecosystem_specific":{"binaries":[{"binary_name":"dnsmasq","binary_version":"2.75-1ubuntu0.16.04.7"},{"binary_name":"dnsmasq-base","binary_version":"2.75-1ubuntu0.16.04.7"},{"binary_name":"dnsmasq-utils","binary_version":"2.75-1ubuntu0.16.04.7"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-25684.json"}},{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.79-1ubuntu0.2"}]}],"versions":["2.78-1","2.78-3","2.79-1"],"ecosystem_specific":{"binaries":[{"binary_name":"dnsmasq","binary_version":"2.79-1ubuntu0.2"},{"binary_name":"dnsmasq-base","binary_version":"2.79-1ubuntu0.2"},{"binary_name":"dnsmasq-base-lua","binary_version":"2.79-1ubuntu0.2"},{"binary_name":"dnsmasq-utils","binary_version":"2.79-1ubuntu0.2"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-25684.json"}},{"package":{"name":"dnsmasq","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/dnsmasq?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.80-1.1ubuntu1.2"}]}],"versions":["2.80-1ubuntu2","2.80-1ubuntu4","2.80-1.1ubuntu1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"2.80-1.1ubuntu1.2","binary_name":"dnsmasq"},{"binary_name":"dnsmasq-base","binary_version":"2.80-1.1ubuntu1.2"},{"binary_version":"2.80-1.1ubuntu1.2","binary_name":"dnsmasq-base-lua"},{"binary_name":"dnsmasq-utils","binary_version":"2.80-1.1ubuntu1.2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-25684.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}