{"id":"CVE-2026-93008","kind":"vulnerability","aliases":["CVE-2026-93008"],"related":[],"title":"dnsmasq: CNAME handling lets upstream poison cache for unrelated names","description":"A flaw was found in dnsmasq. When following a CNAME in a DNS response, the resolver can cache records for the CNAME target without checking that those records belong to the responding server's authorized zone. In split-DNS deployments that send some domains to a specific upstream, an attacker who controls that upstream can inject cache entries for unrelated names. Later clients may then receive attacker-chosen addresses for those names.","summary":"dnsmasq caches records for CNAME targets without checking they belong to the upstream server's authorized zone. An attacker who controls an upstream resolver in a split-DNS setup can plant cache entries for unrelated names, so later clients may receive attacker-chosen addresses.","severity":"medium","cvss":6.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dns","dnsmasq","runtime","self-hosted","split-dns"],"not_affected_if":["no-split-dns","single-upstream-resolver"],"how_to_check":"- Check the installed version with `dnsmasq --version` and compare it to the fixed versions below.\n- Look for split-DNS rules in the dnsmasq configuration (`server=/domain/upstream` lines) that forward some domains to a specific upstream.","fix":null,"status":"open","published_at":"2026-10-29T13:17:16+00:00","first_seen_at":"2026-10-29T13:25:08+00:00","triaged_at":"2026-10-29T13:25:38+00:00","updated_at":"2026-10-29T13:25:38+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-29T13:25:38Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"dnsmasq: CNAME handling lets upstream poison cache for unrelated names","impact":"medium","summary":"dnsmasq caches records for CNAME targets without checking they belong to the upstream server's authorized zone. An attacker who controls an upstream resolver in a split-DNS setup can plant cache entries for unrelated names, so later clients may receive attacker-chosen addresses.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["dnsmasq","dns","split-dns","self-hosted"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"clients receive attacker-chosen addresses for unrelated domain names","analyst_note":"","how_to_check":"- Check the installed version with `dnsmasq --version` and compare it to the fixed versions below.\n- Look for split-DNS rules in the dnsmasq configuration (`server=/domain/upstream` lines) that forward some domains to a specific upstream.\n- unknown","plain_action":"","needs_analyst":false,"not_affected_if":["single-upstream-resolver","no-split-dns"],"who_is_affected":"Exposure requires a split-DNS deployment where some domains are forwarded to a specific upstream resolver that an attacker could control or influence. Systems that forward all queries to a single trusted resolver are less exposed. The sources do not name the affected versions.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.001037,"input_tokens":4133,"output_tokens":1248,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-93008':13A,16A 'address':71B,142C 'attack':44B,69B,122C,140C 'attacker-chosen':68B,139C 'author':41B,106C 'belong':35B,100C 'cach':7A,27B,58B,89C,129C 'check':33B,96C 'chosen':70B,141C 'client':65B,135C 'cname':2A,30B,81C,93C 'control':46B,124C 'cve':11A,14A 'deploy':112C 'dns':17B,25B,54B,84C,111C 'dnsmasq':1A,18B,26B,77C 'domain':116C 'entri':59B,130C 'flaw':73C 'follow':79C 'found':75C 'handl':3A 'host':22B 'inject':128C 'later':64B,134C 'let':4A 'may':66B,136C 'name':10A,62B,133C,145C 'plant':57B 'poison':6A 'receiv':67B,138C 'record':28B,90C,99C 'resolv':49B,87C 'respond':103C 'respons':85C 'runtim':19B 'self':21B 'self-host':20B 'send':114C 'server':39B,104C 'setup':55B 'specif':119C 'split':24B,53B,110C 'split-dn':23B,52B,109C 'target':31B,94C 'unrel':9A,61B,132C 'upstream':5A,38B,48B,120C,126C 'without':32B,95C 'zone':42B,107C","nicknames":[],"mitigations":[],"who_affected":"Exposure requires a split-DNS deployment where some domains are forwarded to a specific upstream resolver that an attacker could control or influence. Systems that forward all queries to a single trusted resolver are less exposed. The sources do not name the affected versions.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"first_public_at":"2026-10-29T13:17:16+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N","cvss_by":"secalert@redhat.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-93008","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93008","severity":null,"published_at":"2026-10-29T13:17:16+00:00","modified_at":"2026-10-29T13:17:16+00:00","first_seen_at":"2026-10-29T13:25:08+00:00","fetched_at":"2026-10-29T13:25:08+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}