CVE-2026-55833 — 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-2026-55833HIGH

Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  N  N  H    7.5   .0042   35.5     —

AFFECTED
  Product  Versions                          Fixed
  netty    >= 4.2.0.Final, < 4.2.16.Final –  —

TIMELINE
  Jun 17  Reserved by GitHub_M
  Jul 20  Published (CNA: GitHub_M)
  Jul 21  EXPLOIT PUBLISHED — CVE-2026-55833 (netty). Public exploit reference added.

CWE-400 · CNA: GitHub_M · CVSS v3.1 · 5 references · NVD status: Analyzed

Description

Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty SPDY header decoding continues inflating zlib-compressed header blocks after the raw header parser has exceeded `maxHeaderSize` and marked the frame truncated in `SpdyFrameCodec`, allowing a remote peer to send a small compressed `HEADERS` block that expands into much larger raw header data and causes compression-amplified CPU and allocation churn. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
June 17, 2026	Reserved	Reserved by GitHub_M
July 20, 2026	Published	Published (CNA: GitHub_M)
July 21, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-55833 (netty). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
netty	netty	—	>= 4.2.0.Final, < 4.2.16.Final	—

Weaknesses

CWE-400

References (5)

https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b [Patch]
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6 [Patch]
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final [Release Notes]
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final [Release Notes]
https://github.com/netty/netty/security/advisories/GHSA-mvh2-crg5-v77c [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-55833 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-2026-55833 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.