{"id":"CVE-2026-123606","aliases":["DEBIAN-CVE-2026-123606","EUVD-2026-119365","GHSA-5p73-2jm7-2cmq","GHSA-6h5c-jjg5-wj59","RUSTSEC-2026-0515","RUSTSEC-2026-0521","UBUNTU-CVE-2026-123606"],"status":"published","title":"Hickory-DNS Recursor 0.25.0-alpha.3 through 0.25.2 Glueless-NS Referral Amplification","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","severity":{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00409,"percentile":0.35714,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400"],"published":"2026-09-03T12:00:00Z","modified":"2026-11-12T14:40:53Z","fixes":[{"ecosystem":"Debian:14","package":"rust-hickory-resolver","fixed_in":["0.26.3-1"],"sources":["osv"]},{"ecosystem":"crates.io","package":"hickory-resolver","fixed_in":["0.26.2"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:13","package":"rust-hickory-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.4-1","0.24.4-2","0.24.4-3","0.24.4-4","0.24.4-5","0.25.2-1","0.25.2-2","0.26.1-1","0.26.3-1"]},{"source":"osv","ecosystem":"Debian:14","package":"rust-hickory-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.26.3-1"}]}],"versions":["0.24.4-1","0.24.4-2","0.24.4-3","0.24.4-4","0.24.4-5","0.25.2-1","0.25.2-2","0.26.1-1"]},{"source":"osv","ecosystem":"crates.io","package":"hickory-resolver","ranges":[{"type":"SEMVER","events":[{"introduced":"0.26.0-beta.1"},{"fixed":"0.26.2"}]}]},{"source":"osv","ecosystem":"crates.io","package":"hickory-recursor","ranges":[{"type":"SEMVER","events":[{"introduced":"0.25.0-alpha.3"}]}]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"rust-hickory-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"rust-hickory-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.4-5","0.26.1-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"rust-hickory-resolver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.4-1","0.24.4-5"]}],"products":[{"vendor":"hickory-dns","product":"hickory-dns"}],"references":[{"url":"https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-6h5c-jjg5-wj59","tags":["vendor-advisory","advisory","report"]},{"url":"https://www.vulncheck.com/advisories/hickory-dns-recursor-0.25.0-alpha.3-through-0.25.2-glueless-ns-referral-amplification","tags":["third-party-advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123606","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-5p73-2jm7-2cmq"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/123xxx/CVE-2026-123606.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-123606","tags":["advisory"]},{"url":"https://crates.io/crates/hickory-resolver","tags":["package"]},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0515.html","tags":["advisory"]},{"url":"https://github.com/hickory-dns/hickory-dns/commit/74062f3a3ef6904b64717dd025945702b2cf4133","tags":["web"]},{"url":"https://github.com/hickory-dns/hickory-dns/commit/47cd005b8f3d190134bbb943d2328ef8a83ade8c","tags":["web"]},{"url":"https://crates.io/crates/hickory-recursor","tags":["package"]},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0521.html","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-123606","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-123606","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-123606","title":"Hickory-DNS Recursor 0.25.0-alpha.3 through 0.25.2 Glueless-NS Referral Amplification","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-08T01:38:32.727Z","modified":"2026-11-09T13:52:33.572Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"},{"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":"cna"}],"cwes":["CWE-400"],"updated_at":"2026-11-08T02:36:49.037074Z"}],"euvd":[{"id":"EUVD-2026-119365","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-08T01:38:32Z","modified":"2026-11-09T13:52:33Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-08T06:12:04.155226Z"}],"ghsa":[{"id":"GHSA-5p73-2jm7-2cmq","title":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0...","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-08T03:30:37Z","modified":"2026-11-08T03:30:44Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","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"}],"cwes":["CWE-400"],"updated_at":"2026-11-08T03:41:54.072675Z"}],"nvd":[{"id":"CVE-2026-123606","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-08T02:16:55.583Z","modified":"2026-11-10T22:15:59.797Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"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-400"],"updated_at":"2026-11-09T16:14:55.503615Z"}],"osv":[{"id":"CVE-2026-123606","title":"Hickory-DNS Recursor 0.25.0-alpha.3 through 0.25.2 Glueless-NS Referral Amplification","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-08T01:38:32.727Z","modified":"2026-11-12T14:40:53.913632545Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-12T14:53:10.251383Z"},{"id":"DEBIAN-CVE-2026-123606","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-08T02:16:55.583Z","modified":"2026-11-11T09:47:36.067331386Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-10T10:26:30.347596Z"},{"id":"UBUNTU-CVE-2026-123606","description":"The hickory-dns recursor in hickory-recursor 0.25.0-alpha.3 through 0.25.2 and hickory-resolver 0.26.0-alpha.1 before 0.26.2 iterates every out-of-bailiwick NS target lacking glue in a referral without any per-query work budget. Remote attackers can serve such referrals to force A and AAAA lookups per target, amplifying traffic against remote servers or exhausting recursor resources.","status":"published","published":"2026-11-09T00:00:00Z","modified":"2026-11-10T02:50:13.277330008Z","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":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-10T03:18:58.105788Z"},{"id":"RUSTSEC-2026-0515","title":"Recursor followed every glueless name server in a referral, with no per-query budget","description":"When a referral listed name servers outside the delegated zone and gave no glue addresses, the recursor looked up A and AAAA records for every listed name server, recursing into each one. Only the chain-depth limits applied. There was no cap on how many name servers it chased per referral or on the total upstream work per client query.\n\nSomeone who controls a zone can return referrals that list many glueless name servers in a victim's domain, and nest them, so that each client query makes the recursor send a large number of queries to the victim's servers (the NXNSAttack pattern). The same can exhaust the recursor's own resources.\n\nThis affects the recursive resolver, which is in hickory-resolver behind the opt-in `recursor` feature from 0.26.0-beta.1. Earlier releases shipped it as the separate hickory-recursor crate.\n\nFrom 0.26.2 the recursor follows at most 5 glueless name servers per delegation and sends at most 200 upstream queries per client request.","status":"published","published":"2026-09-03T12:00:00Z","modified":"2026-11-12T14:40:53.913632545Z","updated_at":"2026-11-12T14:53:10.251383Z"},{"id":"RUSTSEC-2026-0521","title":"Recursor followed every glueless name server in a referral (no fixed hickory-recursor release)","description":"For referrals whose name servers are outside the delegated zone and come without glue, the recursor resolved every listed name server, with no cap on referral width and no per-query work budget. Someone who controls a zone can use this to make each client query send a large number of queries to a victim's servers (the NXNSAttack pattern), or to exhaust the recursor.\n\nThe recursor code moved into hickory-resolver (opt-in `recursor` feature) in 0.26.0-beta.1, and the fix is in hickory-resolver 0.26.2. No hickory-recursor release contains a fix, so users should move to hickory-resolver 0.26.2 or later with the `recursor` feature.","status":"published","published":"2026-09-03T12:00:00Z","modified":"2026-11-12T14:40:53.913632545Z","updated_at":"2026-11-12T14:53:10.251383Z"}]}}