{"id":"CVE-2026-123571","kind":"vulnerability","aliases":["CVE-2026-123571"],"related":[],"title":"Hickory DNS: malformed TSIG record crashes the server with a panic","description":"Hickory DNS from 0.26.0 before 0.26.2 contains an integer underflow vulnerability in TSIG RDATA decoding that allows remote attackers to trigger a panic via malformed records. Attackers can send a crafted TSIG record in DNS wire format to cause unchecked subtraction underflow, crashing builds with overflow checks enabled and causing denial of service.","summary":"Hickory DNS versions from 0.26.0 before 0.26.2 have an integer underflow in how they decode TSIG records. A remote attacker can send a crafted DNS message that makes the server panic, causing denial of service.","severity":"high","cvss":8.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dns","hickory-dns","package","rust"],"not_affected_if":["no-tsig-handling","versions-outside-range"],"how_to_check":null,"fix":"- Hickory DNS: move to `0.26.2` or later","status":"open","published_at":"2026-11-08T02:16:49+00:00","first_seen_at":"2026-11-08T02:21:12+00:00","triaged_at":"2026-11-08T02:22:59+00:00","updated_at":"2026-11-08T02:22:59+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-08T02:22:59Z","model":"claude-haiku-5-5","output":{"fix":"- Hickory DNS: move to `0.26.2` or later","reach":"internet","title":"Hickory DNS: malformed TSIG record crashes the server with a panic","impact":"low","summary":"Hickory DNS versions from 0.26.0 before 0.26.2 have an integer underflow in how they decode TSIG records. A remote attacker can send a crafted DNS message that makes the server panic, causing denial of service.","audience":"businesses","category":"package","nicknames":[],"who_cares":["hickory-dns","dns","rust"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"Remote attackers crash the DNS server, causing denial of service.","analyst_note":"","how_to_check":"- Check the Hickory DNS version the service is built with, for example in `Cargo.lock` for the `hickory-proto` or `hickory-server` crates\n- Look for `hickory-dns` or `hickory-server` versions `0.26.0` or `0.26.1` in dependency trees","plain_action":"","needs_analyst":false,"not_affected_if":["versions-outside-range","no-tsig-handling"],"who_is_affected":"Only deployments running Hickory DNS between 0.26.0 and 0.26.2 are exposed, and the crash happens when a malformed TSIG record reaches the decoder, so a server answering queries from the internet is the main concern. Builds with overflow checks enabled crash; the sources say the subtraction underflow is what triggers the panic, and the sources do not say whether release builds are affected differently.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000718,"input_tokens":4306,"output_tokens":575,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-123571':14A,17A '-2026':13A,16A '0.26.0':28B,62C '0.26.2':30B,64C 'allow':75C 'attack':43B,77C,85C 'build':102C 'caus':55B,97C,108C 'check':105C 'contain':65C 'craft':47B,89C 'crash':6A,101C 'cve':12A,15A 'decod':38B,73C 'denial':56B,109C 'dns':2A,18B,21B,25B,48B,60C,93C 'enabl':106C 'format':95C 'hickori':1A,20B,24B,59C 'hickory-dn':19B 'integ':33B,67C 'make':51B 'malform':3A,83C 'messag':49B 'overflow':104C 'packag':22B 'panic':11A,54B,81C 'rdata':72C 'record':5A,40B,84C,91C 'remot':42B,76C 'rust':23B 'send':45B,87C 'server':8A,53B 'servic':58B,111C 'subtract':99C 'trigger':79C 'tsig':4A,39B,71C,90C 'uncheck':98C 'underflow':34B,68C,100C 'version':26B 'via':82C 'vulner':69C 'wire':94C","nicknames":[],"mitigations":[],"who_affected":"Only deployments running Hickory DNS between 0.26.0 and 0.26.2 are exposed, and the crash happens when a malformed TSIG record reaches the decoder, so a server answering queries from the internet is the main concern. Builds with overflow checks enabled crash; the sources say the subtraction underflow is what triggers the panic, and the sources do not say whether release builds are affected differently.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["dns","hickorydns","high","package","rust"],"campaign_type":null,"search_a":"'-123571':14A,17A '-2026':13A,16A 'crash':6A 'cve':12A,15A 'dns':2A 'hickori':1A 'malform':3A 'panic':11A 'record':5A 'server':8A 'tsig':4A","search_b":"'0.26.0':28B '0.26.2':30B 'attack':43B 'caus':55B 'craft':47B 'decod':38B 'denial':56B 'dns':18B,21B,25B,48B 'hickori':20B,24B 'hickory-dn':19B 'integ':33B 'make':51B 'messag':49B 'packag':22B 'panic':54B 'record':40B 'remot':42B 'rust':23B 'send':45B 'server':53B 'servic':58B 'tsig':39B 'underflow':34B 'version':26B","search_c":"'0.26.0':62C '0.26.2':64C 'allow':75C 'attack':77C,85C 'build':102C 'caus':97C,108C 'check':105C 'contain':65C 'craft':89C 'crash':101C 'decod':73C 'denial':109C 'dns':60C,93C 'enabl':106C 'format':95C 'hickori':59C 'integ':67C 'malform':83C 'overflow':104C 'panic':81C 'rdata':72C 'record':84C,91C 'remot':76C 'send':87C 'servic':111C 'subtract':99C 'trigger':79C 'tsig':71C,90C 'uncheck':98C 'underflow':68C,100C 'via':82C 'vulner':69C 'wire':94C","first_public_at":"2026-09-03T21:26:26+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-2026-123571","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123571","severity":null,"published_at":"2026-11-08T02:16:49+00:00","modified_at":"2026-11-08T02:16:49+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":99293,"url":"https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-x962-5xwx-fr8x","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-09-03T21:26:26+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":99294,"url":"https://www.vulncheck.com/advisories/hickory-dns-from-0.26.0-before-0.26.2-panic-via-tsig-rdata-decoding","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"}