{"id":"CVE-2026-100659","state":"PUBLISHED","title":"Netty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass","description":"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.","publishedAt":"2026-09-26T13:23:26.859Z","updatedAt":"2026-09-28T18:17:29.170Z","severity":{"score":6.9,"label":"Medium","version":"4.0","vector":"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","source":"VulnCheck"},"assigner":"VulnCheck","products":["netty netty"],"affected":[{"vendor":"netty","product":"netty","packageURL":"pkg:maven/io.netty/netty-codec-http3","defaultStatus":"unaffected","versions":[{"version":"4.2.0.Final","status":"affected","lessThan":"4.2.18.Final","versionType":"custom"},{"version":"4.2.18.Final","status":"unaffected","versionType":"custom"}]}],"references":["https://github.com/netty/netty/security/advisories/GHSA-q9pg-8h3j-8hvm","https://www.vulncheck.com/advisories/netty-4.2.0-through-4.2.18-http-3-request-routing-bypass"],"weaknesses":["CWE-444"],"ingestedAt":"2026-10-29T20:10:13.529Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/100xxx/CVE-2026-100659.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-100659","state":"PUBLISHED","datePublished":"2026-09-26T13:23:26.859Z","dateUpdated":"2026-09-28T18:17:29.170Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-09-26T02:33:59.039Z"},"containers":{"cna":{"title":"Netty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"netty","product":"netty","packageURL":"pkg:maven/io.netty/netty-codec-http3","defaultStatus":"unaffected","versions":[{"version":"4.2.0.Final","status":"affected","lessThan":"4.2.18.Final","versionType":"custom"},{"version":"4.2.18.Final","status":"unaffected","versionType":"custom"}]}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-q9pg-8h3j-8hvm","tags":["vendor-advisory"],"name":"GitHub Security Advisory (GHSA-q9pg-8h3j-8hvm)"},{"url":"https://www.vulncheck.com/advisories/netty-4.2.0-through-4.2.18-http-3-request-routing-bypass","name":"VulnCheck Advisory: Netty 4.2.0 through 4.2.18 HTTP/3 Request Routing Bypass","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"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","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":6.9,"baseSeverity":"MEDIUM"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-444","lang":"en","description":"Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-09-27T16:27:45.915Z"},"datePublic":"2026-09-10T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2.0.final","versionEndExcluding":"4.2.18.final"}]}]}],"credits":[{"lang":"en","value":"violetagg","type":"reporter"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-28T18:16:52.799456Z","id":"CVE-2026-100659","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-28T18:17:29.170Z"}}]}}}