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CVE-2026-56746— Netty has a Security Control Bypass via CORS Short-Circuit Failure

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.Final至4.2.15.Final版本和4.1.0.Final至4.1.135.Final版本存在权限许可和访问控制问题漏洞，该漏洞源于起源评估过程中的逻辑运算符错误，可能导致攻击者发送Origin:null标头的请求绕过CorsHandler的短路机制，将未经授权的请求转发到后端应用程序，绕过预期的访问控制。

CVSS 6.5 · Medium EPSS 0.41% · P33

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-2026-56746

Vulnerability Information
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Vulnerability Title
Netty has a Security Control Bypass via CORS Short-Circuit Failure
Source: CVE Program / CVE List V5
Vulnerability Description
Netty is a network application framework for development of protocol servers and clients. Versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, are vulnerable to security control bypass during the origin evaluation process. CorsHandler provides a shortCircuit() configuration designed to reject unauthorized cross-origin requests immediately, acting as a security control before requests reach the application. However, due to a logical operator error in the origin evaluation process, this protection can be entirely bypassed. An attacker can bypass the short-circuit mechanism by sending a request with an Origin: null header. This failure forwards unauthorized requests to the backend application, bypassing intended access controls. 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:R/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
访问控制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Netty 权限许可和访问控制问题漏洞
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.Final至4.2.15.Final版本和4.1.0.Final至4.1.135.Final版本存在权限许可和访问控制问题漏洞，该漏洞源于起源评估过程中的逻辑运算符错误，可能导致攻击者发送Origin:null标头的请求绕过CorsHandler的短路机制，将未经授权的请求转发到后端应用程序，绕过预期的访问控制。
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-2026-56746

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III. Intelligence Information for CVE-2026-56746

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Vendor Advisories for CVE-2026-56746 (1)

Vendor Pages for CVE-2026-56746 (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-2026-56817 Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entit
CVE-2026-56745 Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaust

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-284

V. Comments for CVE-2026-56746

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