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CVE-2026-56745— Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion

Quick assessment

Affected
netty netty
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
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 4.2.0版本至4.2.15版本和4.1.0版本至4.1.135版本存在资源管理错误漏洞，该漏洞源于SpdyHttpDecoder处理器在处理客户端发起的SYN_STREAM帧（FLAG_FIN=0）时分配了池化的ByteBuf，但在远程发送RST_STREAM或内容超过maxContentLength时未释放该ByteBuf，导致本机内存耗尽。

AI Predicted 7.5 Difficulty: Easy EPSS 0.63% · P48

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
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I. Basic Information for CVE-2026-56745

Vulnerability Information
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Vulnerability Title
Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion
Source: CVE Program / CVE List V5
Vulnerability Description
Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, the `SpdyHttpDecoder` handler in Netty's SPDY-to-HTTP codec allocates a pooled `ByteBuf` when processing a client-initiated `SYN_STREAM` frame with `FLAG_FIN=0` and stores the partially constructed `FullHttpRequest` in `messageMap`; when the remote peer sends `RST_STREAM` for that stream or the accumulated content exceeds `maxContentLength`, the decoder removes the entry but does not release the pooled `ByteBuf`, causing native memory exhaustion. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
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 4.2.0版本至4.2.15版本和4.1.0版本至4.1.135版本存在资源管理错误漏洞，该漏洞源于SpdyHttpDecoder处理器在处理客户端发起的SYN_STREAM帧（FLAG_FIN=0）时分配了池化的ByteBuf，但在远程发送RST_STREAM或内容超过maxContentLength时未释放该ByteBuf，导致本机内存耗尽。
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-2026-56745

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III. Intelligence Information for CVE-2026-56745

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Vendor Advisories for CVE-2026-56745 (1)

Vendor Pages for CVE-2026-56745 (2)

Same Patch Batch · netty · 2026-07-21 · 7 CVEs total

CVE-2026-55851 8.7 HIGH Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbo
CVE-2026-56819 7.5 HIGH Netty: HTTP/2 decompression leaks ByteBuf reference count when the decompressor channel is
CVE-2026-56816 7.5 HIGH Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types
CVE-2026-56820 7.4 HIGH Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks
CVE-2026-56746 6.5 MEDIUM Netty has a Security Control Bypass via CORS Short-Circuit Failure
CVE-2026-56817 Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entit

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-56745

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