{"id":"CVE-2026-100660","summary":"Netty before 4.2.18.Final QpackEncoder Unbounded Memory Retention","details":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) from 4.2.0.Final through 4.2.17.Final retains unbounded per-stream QPACK encoder state. QpackEncoder stores a queue and a dynamic-table index tracker for every encoded field section that references the QPACK dynamic table, keyed by the peer-controlled QUIC stream ID, and these entries are released only when the remote decoder sends a Section Acknowledgment or Stream Cancellation instruction — not when the HTTP/3 stream completes. There is no limit on the number of tracked streams, field sections, or retained bytes. A remote, unauthenticated HTTP/3 client can advertise a non-zero QPACK dynamic-table capacity, acknowledge the table insertion so the server reuses a dynamically indexed response header, and then omit all mandatory Section Acknowledgments while issuing sequential requests over a single QUIC connection, bypassing concurrent-stream limits and causing unbounded heap growth until the server exhausts memory (denial of service). Fixed in 4.2.18.Final.","aliases":["GHSA-495p-pchh-r4mc"],"modified":"2026-09-30T03:30:19.280606336Z","published":"2026-09-26T13:23:27.554Z","database_specific":{"cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100660.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100660.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-495p-pchh-r4mc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100660"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/netty-before-4.2.18-final-qpackencoder-unbounded-memory-retention"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/netty/netty","events":[{"introduced":"09e64d259c99be8b5b2a471a78f11e65eb82598a"},{"fixed":"2521f494432e27415a567d3a81a9eb907abf20b3"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"4.2.18.Final"},{"introduced":"4.2.0.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-2026-100660.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:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}