CVE-2026-55831CWE-400CWE-770

Netty SPDY SETTINGS frame count materializes unbounded settings map

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's SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. 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
Weaknesses
CWE-400 · Uncontrolled Resource Consumption; CWE-770 · Allocation of Resources Without Limits or Throttling
Published
2026-07-20T23:00Z
EPSS history
Timeline
  • 20 JUL 23:00Z
    Netty SPDY SETTINGS frame count materializes unbounded settings map
    cvelistv5