{"id":"CVE-2026-123576","kind":"vulnerability","aliases":["CVE-2026-123576"],"related":[],"title":"Hickory DNS: incomplete DNS-over-QUIC requests exhaust server memory","description":"Hickory DNS 0.24.0 through 0.26.1 contains a memory exhaustion vulnerability that allows remote attackers to consume server resources by sending incomplete DNS-over-QUIC request bodies. Attackers can open many connections and send only large length prefixes, causing pre-allocated buffers to persist without timeout and exhausting server memory.","summary":"Hickory DNS, a DNS server library and server, lets a remote attacker open many DNS-over-QUIC connections and send only large length prefixes. The server pre-allocates buffers for those requests that never time out, so memory runs out.","severity":"high","cvss":8.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dns-over-quic","dns-server","hickory-dns","package","rust"],"not_affected_if":["dns-over-quic-disabled","other-dns-software"],"how_to_check":"- Check the Hickory DNS version in your `Cargo.lock` or dependency tree (for example `cargo tree -i hickory-proto` or `cargo tree -i hickory-server`).\n- Look for DNS-over-QUIC listeners enabled on port 853 in your server configuration.","fix":"- Hickory DNS: move to a version above `0.26.1` (the affected range is `0.24.0` through `0.26.1`; the exact fixed version is unknown from these sources).","status":"open","published_at":"2026-11-08T02:16:50+00:00","first_seen_at":"2026-11-08T02:21:12+00:00","triaged_at":"2026-11-08T02:22:53+00:00","updated_at":"2026-11-08T02:22:53+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-08T02:22:53Z","model":"claude-haiku-5-5","output":{"fix":"- Hickory DNS: move to a version above `0.26.1` (the affected range is `0.24.0` through `0.26.1`; the exact fixed version is unknown from these sources).","reach":"internet","title":"Hickory DNS: incomplete DNS-over-QUIC requests exhaust server memory","impact":"medium","summary":"Hickory DNS, a DNS server library and server, lets a remote attacker open many DNS-over-QUIC connections and send only large length prefixes. The server pre-allocates buffers for those requests that never time out, so memory runs out.","audience":"businesses","category":"package","nicknames":[],"who_cares":["hickory-dns","dns-server","dns-over-quic","rust"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"remote attacker exhausts server memory, causing denial of service","analyst_note":"Confirm the fixed version and whether DNS-over-QUIC is enabled by default; check the vendor advisory on github.com and the VulnCheck advisory.","how_to_check":"- Check the Hickory DNS version in your `Cargo.lock` or dependency tree (for example `cargo tree -i hickory-proto` or `cargo tree -i hickory-server`).\n- Look for DNS-over-QUIC listeners enabled on port 853 in your server configuration.","plain_action":"","needs_analyst":true,"not_affected_if":["dns-over-quic-disabled","other-dns-software"],"who_is_affected":"Systems running Hickory DNS 0.24.0 through 0.26.1 with DNS-over-QUIC enabled are exposed, because the flaw is in the QUIC request handling. Servers that only use plain DNS, DNS-over-TLS, or DNS-over-HTTPS are not described as affected by the sources. Resolvers built on other DNS software are not affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.00077,"input_tokens":4294,"output_tokens":681,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-123576':14A,17A '-2026':13A,16A '0.24.0':73C '0.26.1':75C 'alloc':59B,112C 'allow':82C 'attack':41B,84C,98C 'bodi':97C 'buffer':60B,113C 'caus':109C 'connect':48B,102C 'consum':86C 'contain':76C 'cve':12A,15A 'dns':2A,5A,19B,23B,27B,31B,33B,45B,72C,93C 'dns-over-qu':4A,18B,44B,92C 'dns-server':22B 'exhaust':9A,79C,119C 'hickori':1A,26B,30B,71C 'hickory-dn':25B 'incomplet':3A,91C 'larg':52B,106C 'length':53B,107C 'let':38B 'librari':35B 'mani':43B,101C 'memori':11A,69B,78C,121C 'never':65B 'open':42B,100C 'packag':28B 'persist':115C 'pre':58B,111C 'pre-alloc':57B,110C 'prefix':54B,108C 'quic':7A,21B,47B,95C 'remot':40B,83C 'request':8A,63B,96C 'resourc':88C 'run':70B 'rust':29B 'send':50B,90C,104C 'server':10A,24B,34B,37B,56B,87C,120C 'time':66B 'timeout':117C 'vulner':80C 'without':116C","nicknames":[],"mitigations":[],"who_affected":"Systems running Hickory DNS 0.24.0 through 0.26.1 with DNS-over-QUIC enabled are exposed, because the flaw is in the QUIC request handling. Servers that only use plain DNS, DNS-over-TLS, or DNS-over-HTTPS are not described as affected by the sources. Resolvers built on other DNS software are not affected.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["dnsoverquic","dnsserver","hickorydns","high","package","rust"],"campaign_type":null,"search_a":"'-123576':14A,17A '-2026':13A,16A 'cve':12A,15A 'dns':2A,5A 'dns-over-qu':4A 'exhaust':9A 'hickori':1A 'incomplet':3A 'memori':11A 'quic':7A 'request':8A 'server':10A","search_b":"'alloc':59B 'attack':41B 'buffer':60B 'connect':48B 'dns':19B,23B,27B,31B,33B,45B 'dns-over-qu':18B,44B 'dns-server':22B 'hickori':26B,30B 'hickory-dn':25B 'larg':52B 'length':53B 'let':38B 'librari':35B 'mani':43B 'memori':69B 'never':65B 'open':42B 'packag':28B 'pre':58B 'pre-alloc':57B 'prefix':54B 'quic':21B,47B 'remot':40B 'request':63B 'run':70B 'rust':29B 'send':50B 'server':24B,34B,37B,56B 'time':66B","search_c":"'0.24.0':73C '0.26.1':75C 'alloc':112C 'allow':82C 'attack':84C,98C 'bodi':97C 'buffer':113C 'caus':109C 'connect':102C 'consum':86C 'contain':76C 'dns':72C,93C 'dns-over-qu':92C 'exhaust':79C,119C 'hickori':71C 'incomplet':91C 'larg':106C 'length':107C 'mani':101C 'memori':78C,121C 'open':100C 'persist':115C 'pre':111C 'pre-alloc':110C 'prefix':108C 'quic':95C 'remot':83C 'request':96C 'resourc':88C 'send':90C,104C 'server':87C,120C 'timeout':117C 'vulner':80C 'without':116C","first_public_at":"2026-09-03T21:57:55+00:00","kev":null,"cvss_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","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-123576","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123576","severity":null,"published_at":"2026-11-08T02:16:50+00:00","modified_at":"2026-11-08T02:16:50+00:00","first_seen_at":"2026-11-08T02:21:12+00:00","fetched_at":"2026-11-08T02:21:12+00:00","note":null}],"documents":[{"id":99303,"url":"https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-2f4m-fq7w-mrgx","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-09-03T21:57:55+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":99304,"url":"https://www.vulncheck.com/advisories/hickory-dns-0.24.0-through-0.26.1-memory-exhaustion-via-dns-over-quic-requests","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"}