{"id":"CVE-2026-59900","summary":"Netty codec-http2: Lack of Host Header Deduplication in HTTP/2→HTTP/1.x Translation Leads to Request Routing Bypass","details":"Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, Netty's HTTP/2-to-HTTP/1.x translation layer (`Http2StreamFrameToHttpObjectCodec` and `InboundHttp2ToHttpAdapter`) fails to deduplicate or validate `Host` headers when an HTTP/2 client supplies both the `:authority` pseudo-header and a literal `host` header in a single HEADERS frame. The translator maps `:authority` to `Host` and separately copies the literal `host` header, producing an `HttpRequest` object containing two `Host` headers with attacker-controlled differing values. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.","aliases":["GHSA-c69g-56f8-xwqj"],"modified":"2026-07-31T03:49:05.795843239Z","published":"2026-07-29T17:58:35.543Z","related":["CGA-f267-869r-xg8p","openSUSE-SU-2026:11394-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59900.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-444"]},"references":[{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59900.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-c69g-56f8-xwqj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59900"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/netty/netty","events":[{"introduced":"09e64d259c99be8b5b2a471a78f11e65eb82598a"},{"introduced":"0"},{"fixed":"3703d79669ee024f6483c9d8697ac58ba546df33"},{"fixed":"fca0764703b3bb59c6e6dc5d29c6d9710d35c0e6"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"4.2.0.Final"},{"fixed":"4.2.16.Final"},{"introduced":"0"},{"fixed":"4.1.136.Final"}]}}],"versions":["netty-4.1.135.Final","netty-4.2.15.Final","netty-4.1.134.Final","netty-4.2.14.Final","netty-4.1.133.Final","netty-4.2.13.Final","netty-4.2.12.Final","netty-4.1.132.Final","netty-4.2.11.Final","netty-4.1.131.Final","netty-4.2.10.Final","netty-4.2.9.Final","netty-4.1.130.Final","netty-4.2.8.Final","netty-4.1.129.Final","netty-4.1.128.Final","netty-4.2.7.Final","netty-4.2.6.Final","netty-4.1.127.Final","netty-4.2.5.Final","netty-4.1.126.Final","netty-4.1.125.Final","netty-4.2.4.Final","netty-4.1.124.Final","netty-4.1.123.Final","netty-4.2.3.Final","netty-4.2.2.Final","netty-4.1.122.Final","netty-4.2.1.Final","netty-4.1.121.Final","netty-4.1.120.Final","netty-4.2.0.Final","netty-4.1.119.Final","netty-4.1.118.Final","netty-4.1.117.Final","netty-4.1.116.Final","netty-4.1.115.Final","netty-4.1.114.Final","netty-4.1.113.Final","netty-4.1.112.Final","netty-4.1.111.Final","netty-4.1.110.Final","netty-4.1.109.Final","netty-4.1.108.Final","netty-4.1.107.Final","netty-4.1.106.Final","netty-4.1.105.Final","netty-4.1.104.Final","netty-4.1.103.Final","netty-4.1.102.Final","netty-4.1.101.Final","netty-4.1.100.Final","netty-4.1.99.Final","netty-4.1.98.Final","netty-4.1.97.Final","netty-4.1.96.Final","netty-4.1.95.Final","netty-4.1.94.Final","netty-4.1.93.Final","netty-4.1.92.Final","netty-4.1.91.Final","netty-4.1.90.Final","netty-4.1.89.Final","netty-4.1.88.Final","netty-4.1.87.Final","netty-4.1.86.Final","netty-4.1.85.Final","netty-4.1.84.Final","netty-4.1.83.Final","netty-4.1.82.Final","netty-4.1.81.Final","netty-4.1.80.Final","netty-4.1.79.Final","netty-4.1.78.Final","netty-4.1.77.Final","netty-4.1.76.Final","netty-4.1.75.Final","netty-4.1.74.Final","netty-4.1.73.Final","netty-4.1.72.Final","netty-4.1.71.Final","netty-4.1.70.Final","netty-4.1.69.Final","netty-4.1.68.Final","netty-4.1.67.Final","netty-4.1.66.Final","netty-4.1.65.Final","netty-4.1.64.Final","netty-4.1.63.Final","netty-4.1.62.Final","netty-4.1.61.Final","netty-4.1.60.Final","netty-4.1.59.Final","netty-4.1.58.Final","netty-4.1.57.Final","netty-4.1.56.Final","netty-4.1.55.Final","netty-4.1.54.Final","netty-4.1.53.Final","netty-4.1.52.Final","netty-4.1.51.Final","netty-4.1.50.Final","netty-4.1.49.Final","netty-4.1.48.Final","netty-4.1.47.Final","netty-4.1.46.Final","netty-4.1.45.Final","netty-4.1.44.Final","netty-4.1.43.Final","netty-4.1.42.Final","netty-4.1.41.Final","netty-4.1.40.Final","netty-4.1.39.Final","netty-4.1.38.Final","netty-4.1.37.Final","netty-4.1.36.Final","netty-4.1.35.Final","netty-4.1.34.Final","netty-4.1.33.Final","netty-4.1.32.Final","netty-4.1.31.Final","netty-4.1.30.Final","netty-4.1.29.Final","netty-4.1.28.Final","netty-4.1.27.Final","netty-4.1.26.Final","netty-4.1.25.Final","netty-4.1.24.Final","netty-4.1.23.Final","netty-4.1.22.Final","netty-4.1.21.Final","netty-4.1.20.Final","netty-4.1.19.Final","netty-4.1.18.Final","netty-4.1.17.Final","netty-4.1.16.Final","netty-4.1.15.Final","netty-4.1.14.Final","netty-4.1.13.Final","netty-4.1.12.Final","netty-4.1.11.Final","netty-4.1.10.Final","netty-4.1.9.Final","netty-4.1.8.Final","netty-4.1.7.Final","netty-4.1.6.Final","netty-4.1.5.Final","netty-4.1.4.Final","netty-4.1.3.Final","netty-4.1.2.Final","netty-4.1.1.Final","netty-4.1.0.Final","netty-4.1.0.CR7","netty-4.1.0.CR6","netty-4.1.0.CR5","netty-4.1.0.CR4","netty-4.1.0.CR3","netty-4.1.0.CR2","netty-4.1.0.CR1","netty-4.1.0.Beta8","netty-4.1.0.Beta7","netty-4.1.0.Beta6","netty-4.1.0.Beta5","netty-4.1.0.Beta4","netty-4.1.0.Beta3","netty-4.1.0.Beta2","netty-4.1.0.Beta1","netty-4.0.15.Final","netty-4.0.14.Final","netty-4.0.14.Beta1","netty-4.0.13.Final","netty-4.0.12.Final","netty-4.0.11.Final","netty-4.0.10.Final","netty-4.0.8.Final","netty-4.0.7.Final","ne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