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CVE-2026-55831— Netty SPDY SETTINGS frame count materializes unbounded settings map

Quick assessment

Affected
netty netty
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Netty是Netty团队开源的一款非阻塞I/O客户端-服务器框架,它主要用于开发Java网络应用程序,如协议服务器和客户端等。 Netty 4.1.136.Final之前版本和4.2.16.Final之前版本存在资源管理错误漏洞，该漏洞源于SPDY SETTINGS解码器接受对等方声明的SETTINGS条目计数高达24位帧长度限制，并在DefaultSpdySettingsFrame中物化每个唯一的设置ID，允许远程SPDY/3.1对等方发送语法有效的约2 MiB SETTINGS帧，创建262144个

CVSS 7.5 · High EPSS 0.66% · P50

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
netty netty >= 4.2.0.Final, < 4.2.16.Final affected
>= 4.1.0.Final, < 4.1.136.Final affected
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I. Basic Information for CVE-2026-55831

Vulnerability Information
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Vulnerability Title
Netty SPDY SETTINGS frame count materializes unbounded settings map
Source: CVE Program / CVE List V5
Vulnerability 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'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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
Netty 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Netty是Netty团队开源的一款非阻塞I/O客户端-服务器框架,它主要用于开发Java网络应用程序,如协议服务器和客户端等。 Netty 4.1.136.Final之前版本和4.2.16.Final之前版本存在资源管理错误漏洞，该漏洞源于SPDY SETTINGS解码器接受对等方声明的SETTINGS条目计数高达24位帧长度限制，并在DefaultSpdySettingsFrame中物化每个唯一的设置ID，允许远程SPDY/3.1对等方发送语法有效的约2 MiB SETTINGS帧，创建262144个
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
netty netty >= 4.2.0.Final, < 4.2.16.Final -

II. Public POCs for CVE-2026-55831

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 10010 chars
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III. Intelligence Information for CVE-2026-55831

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Vendor Advisories for CVE-2026-55831 (1)

Vendor Pages for CVE-2026-55831 (2)

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-770

V. Comments for CVE-2026-55831

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