Is CVE-2026-56746 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-56746 being exploited in the wild.

How severe is CVE-2026-56746?

Medium severity, with a CVSS score of 6.5, published 21 July 2026.

Which products and versions are affected?

io.netty:netty-codec-http (Maven) ECOSYSTEM:introduced=4.2.0.Final,fixed=4.2.16.Final; Netty Project Codec HTTP 4.1.0.Final to 4.1.135.Final, 4.2.0.Final to 4.2.15.Final.

Is there a fix for CVE-2026-56746?

Yes. io.netty:netty-codec-http (Maven): upgrade to 4.2.16.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-56746 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-56746?

Check whether you run io.netty:netty-codec-http (Maven), Netty Project Codec HTTP or Netty Project Netty codec-http at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-56746: Netty security bypass in CorsHandler origin evaluation

CVE-2026-56746 · Severity: medium · CVSS 6.5 · Published 2026-07-21

Netty, a widely used networking framework for Java applications, contains a flaw in its Cross-Origin Resource Sharing (CORS) protection mechanism. This security feature is intended to block unauthorized web requests from reaching a backend application. An attacker can bypass these restrictions, potentially allowing unauthorized web-based interactions with the application that should have been blocked.

Technologies: io.netty:netty-codec-http (Maven), Netty Project Codec HTTP. Vendors: Maven, Netty Project.

Quick answers

Is CVE-2026-56746 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-56746 being exploited in the wild.
How severe is CVE-2026-56746?: Medium severity, with a CVSS score of 6.5, published 21 July 2026.
Which products and versions are affected?: io.netty:netty-codec-http (Maven) ECOSYSTEM:introduced=4.2.0.Final,fixed=4.2.16.Final; Netty Project Codec HTTP 4.1.0.Final to 4.1.135.Final, 4.2.0.Final to 4.2.15.Final.
Is there a fix for CVE-2026-56746?: Yes. io.netty:netty-codec-http (Maven): upgrade to 4.2.16.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-56746 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-56746?: Check whether you run io.netty:netty-codec-http (Maven), Netty Project Codec HTTP or Netty Project Netty codec-http at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

io.netty:netty-codec-http (Maven): upgrade to 4.2.16.Final or later

# set io.netty:netty-codec-http to 4.2.16.Final in your pom.xml or build.gradle

Technical details

A logic error exists in io.netty.handler.codec.http.cors.CorsHandler where the short-circuit mechanism, intended to reject unauthorized origins before they reach the backend, can be bypassed. The getForOrigin method incorrectly returns a configuration object when an 'Origin: null' header is received, regardless of whether the developer has explicitly allowed null origins via isNullOriginAllowed(). This causes the short-circuit check to evaluate as false, forwarding the unauthorized request to the backend application. The vulnerability is tracked as CVE-2026-56746 and is resolved in versions 4.1.136.Final and 4.2.16.Final.

Affected products

Netty netty-codec-http >= 4.2.0.Final, < 4.2.16.Final; < 4.1.136.Final

Identifiers

CVE-2026-56746
GHSA-6cqp-g7gg-8hr5

Timeline

2026-07-20: disclosed
2026-07-21: advisory: NVD publication date
2026-07-22: patched: GitHub Advisory published/reviewed

References

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