CVE-2026-55833CWE-400

Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation

High · published July 20, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
51.2
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00665 · 51.2th percentile
Weakness
CWE-400 · Uncontrolled Resource Consumption
Published
2026-07-20T23:18Z
EPSS history
Timeline
  • 20 JUL 23:18Z
    Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation
    cvelistv5