{"schema":"threatline.record/2","record":{"id":"CVE-2026-100664","aliases":["GHSA-hfr2-x62w-v49h"],"summary":"Netty 4.2.2 through 4.2.17 HTTP/1 Host Header Authority Confusion","details":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.2.Final through 4.2.17.Final builds the HTTP/3 :authority pseudo-header from the HTTP/1 Host header before considering the authority of an absolute-form HTTP/1 request-target. In HttpConversionUtil.toHttp3Headers(HttpMessage, boolean) — reached via Http3FrameToHttpObjectCodec(false) — a non-empty Host header takes precedence over the request-target authority, contrary to the HTTP/1.1 rule that a server receiving an absolute-form request-target must ignore the Host header. In a Netty-based HTTP/1-to-HTTP/3 gateway, proxy, or protocol bridge, a remote client can send a request such as \"GET https://trusted.example/admin HTTP/1.1\" with \"Host: attacker.example\", causing components that validate, authorize, or route on the RFC-defined request-target authority to reach a different decision than the upstream HTTP/3 peer, which receives :authority derived from the conflicting Host header. This authority confusion can affect virtual-host routing, allow-list checks, backend selection, cache keys, and URL generation. The advisory reports integrity impact only (no code execution, memory corruption, or availability impact). Fixed in 4.2.18.Final.","categories":["Frameworks"],"product":"netty","vendor":"netty","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-100664","source_modified_at":"2026-09-28T16:47:05.471Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"netty","vendor":"netty","versions":[{"version":"4.2.2.Final","status":"affected","versionType":"custom","lessThan":"4.2.18.Final"},{"version":"4.2.18.Final","status":"unaffected","versionType":"custom"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-100664","source_modified_at":"2026-09-28T16:47:05.471Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"netty","ecosystem":null},"version":"4.2.18.Final","basis":"first unaffected version stated in the CVE record"}],"cvss":8.7,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00329,"percentile":0.24819,"score_date":"2026-10-23"},"published_at":"2026-09-26T13:23:30.478Z","modified_at":"2026-09-28T16:47:05.471Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-100664","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-28T16:47:05.471Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-100664","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/netty/netty/security/advisories/GHSA-hfr2-x62w-v49h","tags":["vendor-advisory"]},{"source":"CVE List","url":"https://www.vulncheck.com/advisories/netty-4.2.2-through-4.2.15-http-1-host-header-authority-confusion","tags":["third-party-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-09-28T16:46:54.123062Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-09-28T16:47:05.471Z","content_hash":"ff5186dae3e17c5ef53137f4ebc11a2d59290a08139a9cb201c4053e9918cc76"}}