CVE-2026-56816 — Security Box Score

CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-56816HIGH

Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  N  N  H    7.5   .0052   42.1     —

AFFECTED
  Product  Versions          Fixed
  netty    < 4.2.16.Final –  —

TIMELINE
  Jun 23  Reserved by GitHub_M
  Jul 21  EXPLOIT PUBLISHED — CVE-2026-56816 (netty). Public exploit reference added.
  Jul 21  Published (CNA: GitHub_M)
  Aug 7   EXPLOIT PUBLISHED — CVE-2026-56816 (netty). Public exploit reference added.

CWE-400 · CNA: GitHub_M · CVSS v3.1 · 3 references · NVD status: Analyzed

Description

Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
June 23, 2026	Reserved	Reserved by GitHub_M
July 21, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-56816 (netty). Public exploit reference added.
July 21, 2026	Published	Published (CNA: GitHub_M)
August 7, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-56816 (netty). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
netty	netty	—	< 4.2.16.Final	—

Weaknesses

CWE-400

References (3)

https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b [Patch]
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final [Release Notes]
https://github.com/netty/netty/security/advisories/GHSA-hpcc-26xq-25fv [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-56816 at cve.org

Vendors: netty

Weaknesses: CWE-400

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-56816 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.