{"id":"CVE-2026-100666","revision":null,"records":[{"revision":"cb7ba3a0ca834f96945c545a7dfaa28a","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-100666","aliases":[],"title":"Netty 4.2.0 through 4.2.16 Response Desynchronization via HttpServerCodec","description":"Netty's HttpServerCodec (io.netty:netty-codec-http) in versions 4.2.0.Final through 4.2.16.Final and in versions up to and including 4.1.136.Final pairs each outbound response with an inbound request by calling pollMethod() once per response, including for 1xx informational responses. If a client pipelines an HTTP/1.1 GET carrying an Expect: 100-continue header followed by a HEAD request, the 100 Continue response consumes the queued GET method, so the subsequent 200 OK for the GET is paired with HEAD and its body is dropped, while the following 200 OK for the HEAD request is written with a body. This desynchronizes HTTP parsing on the connection: the GET entity is never delivered and the HEAD response body is interpreted as the GET body, resulting in response splitting and unsafe connection reuse. Fixed in 4.2.17.Final and 4.1.137.Final.","state":0,"publishedAt":"2026-09-26T13:23:31.961+00:00","modifiedAt":"2026-09-30T14:54:46.509+00:00","affected":[{"ecosystem":"Vendor product","name":"netty","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"netty\",\n                    \"product\": \"netty\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"packageURL\": \"pkg:maven/io.netty/netty-codec-http\",\n                    \"versions\": [\n                        {\n                            \"version\": \"4.2.0.Final\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"custom\",\n                            \"lessThan\": \"4.2.17.Final\"\n                        },\n                        {\n                            \"version\": \"4.2.17.Final\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"custom\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"netty","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"netty\",\n                    \"product\": \"netty\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"packageURL\": \"pkg:maven/io.netty/netty-codec-http\",\n                    \"versions\": [\n                        {\n                            \"version\": \"0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"custom\",\n                            \"lessThan\": \"4.1.137.Final\"\n                        },\n                        {\n                            \"version\": \"4.1.137.Final\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"custom\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N","score":6.9,"severity":"MEDIUM"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","score":7.3,"severity":"HIGH"}],"references":["https://github.com/netty/netty/security/advisories/GHSA-2g6j-r8q9-5hr8","https://www.vulncheck.com/advisories/netty-4.2.0-through-4.2.17-response-desynchronization-via-httpservercodec"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-100666","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-100666","identifiers":["CVE-2026-100666"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-12T03:56:46.1287087+00:00","complete":true,"records":1779,"lastAttemptAt":"2026-11-12T03:56:46.1287087+00:00","lastSuccessAt":"2026-11-12T03:56:46.266109+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:46.2661097+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-64752486c567b55b31fb0d7225f5222bcd0019564ac0ac5f0649e242c7b19299-beddb039e9e8d22605e2eaa29616069a8dbcaa39d8913522266b856ccc773385","complete":true,"records":424562,"lastAttemptAt":"2026-11-12T03:56:45.0720206+00:00","lastSuccessAt":"2026-11-12T03:56:45.0520395+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.0720206+00:00","snapshotPublishedAt":"2026-11-12T03:29:06+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-83f01e9b693347759bbcba1498652358","complete":false,"records":13760,"lastAttemptAt":"2026-11-12T04:06:30.4778921+00:00","lastSuccessAt":"2026-11-12T04:06:30.473+00:00","error":"350 identifier lookups failed; latest failures include AccessDenied (HTTP 403). Other identifiers were checked independently.","lastVerifiedAt":"2026-11-12T04:06:30.473+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13463,"expectedIdentifiers":13813,"failedIdentifiers":350},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-12T03:56:46.1287087+00:00","complete":true,"records":1097,"lastAttemptAt":"2026-11-12T03:56:46.1287087+00:00","lastSuccessAt":"2026-11-12T03:56:46.2668013+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:46.2668014+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-52451a58cbcb4287967102045f86ce70","complete":true,"records":13760,"lastAttemptAt":"2026-11-12T03:56:47.5828253+00:00","lastSuccessAt":"2026-11-12T03:56:47.579+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:47.579+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13813,"expectedIdentifiers":13813,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-3562b6c78fd1bd0f0b55daf66a0926ae24f65e462df7f6d928caad458fc696bf","complete":true,"records":9947,"lastAttemptAt":"2026-11-12T03:56:45.7079161+00:00","lastSuccessAt":"2026-11-11T04:27:43.6877707+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.7079161+00:00","snapshotPublishedAt":"2026-11-11T03:32:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-456002455e0ab94bb92c95476d4e6d175c104cd594749982afd96c893728ecbc","complete":true,"records":2010,"lastAttemptAt":"2026-11-12T03:56:45.2248127+00:00","lastSuccessAt":"2026-11-11T02:36:58.1276999+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.2248127+00:00","snapshotPublishedAt":"2026-11-11T01:17:51+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-baa8362b4daf9e5f39d5563775a55935e7b442c0735d33274a921579ce4a0d66","complete":true,"records":3093,"lastAttemptAt":"2026-11-12T03:56:46.0887439+00:00","lastSuccessAt":"2026-11-11T13:00:02.5446881+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:46.0887439+00:00","snapshotPublishedAt":"2026-11-11T12:47:47+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-685fe7fb2b690656c910a1ea42a9d294e8353311ac8ecfa691a9b0ff1b328804","complete":true,"records":231695,"lastAttemptAt":"2026-11-12T03:56:45.6007038+00:00","lastSuccessAt":"2026-11-11T21:58:47.7265713+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.6007038+00:00","snapshotPublishedAt":"2026-11-11T21:48:35+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}