Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-55833— Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation

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标头解码在原始标头解析器超过maxHeaderSize后继续解压zlib压缩标头块，允许远程对等端发送小型压缩HEADERS块，扩展成更大原始标头数据，导致CPU和内存分配大量消耗。

CVSS 7.5 · High EPSS 0.66% · P50

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

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
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-55833

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation
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 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.
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
未加控制的资源消耗(资源穷尽)
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标头解码在原始标头解析器超过maxHeaderSize后继续解压zlib压缩标头块，允许远程对等端发送小型压缩HEADERS块，扩展成更大原始标头数据，导致CPU和内存分配大量消耗。
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-2026-55833

# POC Description Source Link Shenlong Link
AI-Generated POC Verified env Premium
Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
Success marker: VULNERABLE: SpdyHeaderBlockZlibDecoder kept inflating after maxHeaderSize=8192 truncation; inflater produced 16777234 bytes (>= 2048x the cap). PROOF_7887ff0760fc2197
Reproduction recording is a Pro+ exclusive
Watch the full sandbox build + live exploit recording for this CVE. Limited-time ¥499/mo.
Upgrade to Pro+
claude_code · 11223 chars
GitHub 复现环境（可 clone 直接跑）
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

III. Intelligence Information for CVE-2026-55833

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-55833 (1)

Vendor Pages for CVE-2026-55833 (2)

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-400

V. Comments for CVE-2026-55833

No comments yet

Leave a comment