{"id":"CVE-2026-123584","kind":"vulnerability","aliases":["CVE-2026-123584"],"related":[],"title":"Hickory DNS: malformed UDP reply stops the client listener, denying service","description":"The hickory-net crate in Hickory DNS 0.26.0 before 0.26.2 stops listening and returns an error when a client UDP connection receives a datagram that cannot be parsed as a DNS message. Remote attackers who guess the query's source port, without knowing the transaction ID, can spoof malformed responses to abort client queries, causing denial of service.","summary":"The hickory-net Rust crate in Hickory DNS 0.26.0 stops listening and returns an error when a UDP client receives a datagram it cannot parse as DNS. A remote attacker who guesses the query's source port can spoof malformed responses and abort client queries, causing denial of service.","severity":"high","cvss":8.2,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dns-client","hickory-dns","package","rust"],"not_affected_if":["tcp-only-queries","version-0.26.2-or-later"],"how_to_check":"- Check the `hickory-net` version in `Cargo.lock` or `cargo tree -i hickory-net`\n- Confirm whether the application uses the `hickory-net` UDP client directly or through another Hickory crate","fix":"- `hickory-net` `0.26.2`","status":"open","published_at":"2026-11-08T02:16:52+00:00","first_seen_at":"2026-11-08T02:21:13+00:00","triaged_at":"2026-11-08T02:23:18+00:00","updated_at":"2026-11-08T02:23:18+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-08T02:23:18Z","model":"claude-haiku-5-5","output":{"fix":"- `hickory-net` `0.26.2`","reach":"network","title":"Hickory DNS: malformed UDP reply stops the client listener, denying service","impact":"low","summary":"The hickory-net Rust crate in Hickory DNS 0.26.0 stops listening and returns an error when a UDP client receives a datagram it cannot parse as DNS. A remote attacker who guesses the query's source port can spoof malformed responses and abort client queries, causing denial of service.","audience":"developers","category":"package","nicknames":[],"who_cares":["rust","hickory-dns","dns-client"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"remote attacker aborts DNS client queries, causing denial of service","analyst_note":"","how_to_check":"- Check the `hickory-net` version in `Cargo.lock` or `cargo tree -i hickory-net`\n- Confirm whether the application uses the `hickory-net` UDP client directly or through another Hickory crate","plain_action":"","needs_analyst":false,"not_affected_if":["version-0.26.2-or-later","tcp-only-queries"],"who_is_affected":"Applications built in Rust that use the hickory-net crate as a UDP DNS client at version 0.26.0 before 0.26.2 are exposed. Servers that only run Hickory as a DNS server, or clients on other versions, are not in the stated range. Exposure depends on the client sending queries over UDP to resolvers an attacker can spoof.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000708,"input_tokens":4291,"output_tokens":557,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-123584':14A,17A '-2026':13A,16A '0.26.0':35B,84C '0.26.2':86C 'abort':69B,128C 'attack':56B,110C 'cannot':50B,102C 'caus':72B,131C 'client':8A,20B,45B,70B,95C,129C 'connect':97C 'crate':31B,80C 'cve':12A,15A 'datagram':48B,100C 'deni':10A 'denial':73B,132C 'dns':2A,19B,23B,34B,53B,83C,107C 'dns-client':18B 'error':41B,92C 'guess':58B,112C 'hickori':1A,22B,28B,33B,78C,82C 'hickory-dn':21B 'hickory-net':27B,77C 'id':122C 'know':119C 'listen':9A,37B,88C 'malform':3A,66B,125C 'messag':108C 'net':29B,79C 'packag':24B 'pars':51B,104C 'port':63B,117C 'queri':60B,71B,114C,130C 'receiv':46B,98C 'remot':55B,109C 'repli':5A 'respons':67B,126C 'return':39B,90C 'rust':25B,30B 'servic':11A,75B,134C 'sourc':62B,116C 'spoof':65B,124C 'stop':6A,36B,87C 'transact':121C 'udp':4A,44B,96C 'without':118C","nicknames":[],"mitigations":[],"who_affected":"Applications built in Rust that use the hickory-net crate as a UDP DNS client at version 0.26.0 before 0.26.2 are exposed. Servers that only run Hickory as a DNS server, or clients on other versions, are not in the stated range. Exposure depends on the client sending queries over UDP to resolvers an attacker can spoof.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["dnsclient","hickorydns","high","package","rust"],"campaign_type":null,"search_a":"'-123584':14A,17A '-2026':13A,16A 'client':8A 'cve':12A,15A 'deni':10A 'dns':2A 'hickori':1A 'listen':9A 'malform':3A 'repli':5A 'servic':11A 'stop':6A 'udp':4A","search_b":"'0.26.0':35B 'abort':69B 'attack':56B 'cannot':50B 'caus':72B 'client':20B,45B,70B 'crate':31B 'datagram':48B 'denial':73B 'dns':19B,23B,34B,53B 'dns-client':18B 'error':41B 'guess':58B 'hickori':22B,28B,33B 'hickory-dn':21B 'hickory-net':27B 'listen':37B 'malform':66B 'net':29B 'packag':24B 'pars':51B 'port':63B 'queri':60B,71B 'receiv':46B 'remot':55B 'respons':67B 'return':39B 'rust':25B,30B 'servic':75B 'sourc':62B 'spoof':65B 'stop':36B 'udp':44B","search_c":"'0.26.0':84C '0.26.2':86C 'abort':128C 'attack':110C 'cannot':102C 'caus':131C 'client':95C,129C 'connect':97C 'crate':80C 'datagram':100C 'denial':132C 'dns':83C,107C 'error':92C 'guess':112C 'hickori':78C,82C 'hickory-net':77C 'id':122C 'know':119C 'listen':88C 'malform':125C 'messag':108C 'net':79C 'pars':104C 'port':117C 'queri':114C,130C 'receiv':98C 'remot':109C 'respons':126C 'return':90C 'servic':134C 'sourc':116C 'spoof':124C 'stop':87C 'transact':121C 'udp':96C 'without':118C","first_public_at":"2026-09-03T21:46:43+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:H/AT:P/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","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-123584","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123584","severity":null,"published_at":"2026-11-08T02:16:52+00:00","modified_at":"2026-11-08T02:16:52+00:00","first_seen_at":"2026-11-08T02:21:13+00:00","fetched_at":"2026-11-08T02:21:13+00:00","note":null}],"documents":[{"id":99319,"url":"https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-v44v-c8m4-gc43","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-09-03T21:46:43+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":99320,"url":"https://www.vulncheck.com/advisories/hickory-dns-0.26.0-before-0.26.2-udp-client-denial-of-service-via-spoofed-responses","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}