CVE-2026-56746

Netty has a Security Control Bypass via CORS Short-Circuit Failure

MEDIUM

6.5

CVSS Score

Published: July 21, 2026 at 09:36 PM UTC

Updated: July 30, 2026 at 06:22 PM UTC

1 product affected across 1 vendorNetty

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Netty · Nettymaven

95%

v < 4.1.136.Finalv < 4.2.16.Final4.1.0 ≤ v < 4.1.1364.2.0 ≤ v < 4.2.16

Affected range stops below 4.1.136, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.1.136.Final, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.16, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.16.Final, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://github.com/netty/netty/security/advisories/GHSA-6cqp-g7gg-8hr5

References (3)

x_refsource_CONFIRMVendor Advisory

Source: cverecord

https://github.com/netty/netty/security/advisories/GHSA-6cqp-g7gg-8hr5

x_refsource_MISCRelease Notes

Source: cverecord

https://github.com/netty/netty/releases/tag/netty-4.1.136.Final

x_refsource_MISCRelease Notes

Source: cverecord

https://github.com/netty/netty/releases/tag/netty-4.2.16.Final

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: REQUIRED
Scope: UNCHANGED
Confidentiality: NONE
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-284

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