{"id":"CVE-2026-100662","revision":null,"records":[{"revision":"ee2586a3d50f4be5913071ba32120c43","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-100662","aliases":[],"title":"Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","state":0,"publishedAt":"2026-09-26T13:23:28.99+00:00","modifiedAt":"2026-09-30T14:53:30.335+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-http3\",\n                    \"versions\": [\n                        {\n                            \"version\": \"4.2.0.Final\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"custom\",\n                            \"lessThan\": \"4.2.18.Final\"\n                        },\n                        {\n                            \"version\": \"4.2.18.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:N/VI:N/VA:H/SC:N/SI:N/SA:N","score":8.7,"severity":"HIGH"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://github.com/netty/netty/security/advisories/GHSA-f64r-x647-cg8w","https://www.vulncheck.com/advisories/netty-http-3-qpack-encoder-stream-unbounded-memory-exhaustion-dos"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-100662","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-100662","identifiers":["CVE-2026-100662"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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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. 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