{"id":"CVE-2023-26249","aliases":["DEBIAN-CVE-2023-26249","EUVD-2023-30073","GHSA-38wr-pjxc-vgf7","UBUNTU-CVE-2023-26249"],"status":"published","title":"Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification...","description":"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.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.00708,"percentile":0.5378,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2023-02-21T00:00:00Z","modified":"2026-10-28T02:31:01Z","fixes":[{"ecosystem":"Debian:12","package":"knot-resolver","fixed_in":["5.6.0-1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"knot-resolver","fixed_in":["5.6.0-1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"knot-resolver","fixed_in":["5.6.0-1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.6.0-1"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.6.0-1"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"knot-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.6.0-1"}]}]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"knot-resolver","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"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"knot-resolver","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"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"knot-resolver","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"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"knot-resolver","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"]}],"products":[{"vendor":"nic","product":"knot_resolver"}],"references":[{"url":"https://www.knot-resolver.cz/2023-01-26-knot-resolver-5.6.0.html","tags":["x_transferred","Release Notes","Vendor Advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-26249","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-38wr-pjxc-vgf7"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/26xxx/CVE-2023-26249.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2023-26249","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2023-26249","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-26249","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2023-26249","description":"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.","status":"published","published":"2023-02-21T00:00:00Z","modified":"2025-03-14T18:32:24.994Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"adp"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:35:15.434947Z"}],"euvd":[{"id":"EUVD-2023-30073","description":"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.","status":"published","published":"2023-02-21T00:00:00Z","modified":"2025-03-14T18:32:24Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T20:53:02.719002Z"}],"ghsa":[{"id":"GHSA-38wr-pjxc-vgf7","title":"Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification...","description":"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.","status":"published","published":"2023-02-21T03:30:19Z","modified":"2023-03-10T05:05:45Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:54:18.225969Z"}],"nvd":[{"id":"CVE-2023-26249","description":"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.","status":"published","published":"2023-02-21T02:15:10.293Z","modified":"2026-06-17T05:42:54.013Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:07:47.623983Z"}],"osv":[{"id":"CVE-2023-26249","description":"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.","status":"published","published":"2023-02-21T00:00:00Z","modified":"2026-10-28T02:31:01.316777369Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:31.135751Z"},{"id":"DEBIAN-CVE-2023-26249","description":"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.","status":"published","published":"2023-02-21T02:15:10.293Z","modified":"2026-10-26T18:00:39.497289655Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:39.369204Z"},{"id":"UBUNTU-CVE-2023-26249","description":"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.","status":"published","published":"2023-02-21T02:15:00Z","modified":"2026-04-22T14:04:01.238115Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T16:54:20.198616Z"}]}}