{"id":"CVE-2026-100659","summary":"Netty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass","details":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) in versions 4.2.0.Final through 4.2.17.Final does not enforce the RFC 9114 requirement that the :authority pseudo-header field and a literal host header field, when both present, carry the same value. A remote unauthenticated peer can send a single HEADERS frame containing both fields with differing, attacker-controlled values; the request is accepted and delivered to the application with two conflicting authorities, allowing routing, virtual-host, and access-control decisions to be bypassed when different components in the request path consult different fields. This issue is fixed in 4.2.18.Final.","aliases":["GHSA-q9pg-8h3j-8hvm"],"modified":"2026-09-29T03:31:02.549163226Z","published":"2026-09-26T13:23:26.859Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-444"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100659.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100659.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-q9pg-8h3j-8hvm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100659"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/netty-4.2.0-through-4.2.18-http-3-request-routing-bypass"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/netty/netty","events":[{"introduced":"09e64d259c99be8b5b2a471a78f11e65eb82598a"},{"fixed":"2521f494432e27415a567d3a81a9eb907abf20b3"}],"database_specific":{"extracted_events":[{"introduced":"4.2.0.Final"},{"fixed":"4.2.18.Final"},{"fixed":"4.2.17.Final"}],"source":["AFFECTED_FIELD","DESCRIPTION"]}}],"versions":["netty-clang-bin","netty-4.2.17.Final","netty-4.2.16.Final","netty-4.2.15.Final","netty-4.2.14.Final","netty-4.2.13.Final","netty-4.2.12.Final","netty-4.2.11.Final","netty-4.2.10.Final","netty-4.2.9.Final","netty-4.2.8.Final","netty-4.2.7.Final","netty-4.2.6.Final","netty-4.2.5.Final","netty-4.2.4.Final","netty-4.2.3.Final","netty-4.2.2.Final","netty-4.2.1.Final","netty-4.2.0.Final"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-100659.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"}]}