{"id":"UBUNTU-CVE-2023-26249","details":"Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification attacks and potentially causing a denial of service. Specifically, a single client query may lead to a hundred TCP connection attempts if a DNS server closes connections without providing a response.","modified":"2026-04-22T14:04:01.238115Z","published":"2023-02-21T02:15:00Z","upstream":["CVE-2023-26249"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2023-26249"},{"type":"REPORT","url":"https://www.knot-resolver.cz/2023-01-26-knot-resolver-5.6.0.html"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2023-26249"}],"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/2023/UBUNTU-CVE-2023-26249.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/2023/UBUNTU-CVE-2023-26249.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"}]}],"versions":["3.2.1-3","3.2.1-3ubuntu1","3.2.1-3ubuntu2","3.2.1-3ubuntu2.1","3.2.1-3ubuntu2.2"],"ecosystem_specific":{"binaries":[{"binary_name":"knot-resolver","binary_version":"3.2.1-3ubuntu2.2"},{"binary_version":"3.2.1-3ubuntu2.2","binary_name":"knot-resolver-module-http"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-26249.json"}},{"package":{"name":"knot-resolver","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/knot-resolver@5.4.4-1ubuntu0.1~esm1?arch=source&distro=esm-apps/jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.3.1-1","5.4.2-1","5.4.3-1","5.4.4-1","5.4.4-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"knot-resolver","binary_version":"5.4.4-1ubuntu0.1~esm1"},{"binary_version":"5.4.4-1ubuntu0.1~esm1","binary_name":"knot-resolver-module-http"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-26249.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"}]}