CVE-2026-56746

MEDIUMCVSS 6.5/10EPSS 0.43%

Last modified

CVE-2026-56746 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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. EPSS estimates a 0.43% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS Probability
0.43%

35.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
NettyNetty>= 4.1.0, < 4.1.136
NettyNetty>= 4.2.0, < 4.2.16

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-56746?
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.
How severe is CVE-2026-56746?
CVE-2026-56746 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.43% probability of exploitation in the next 30 days.
How do I fix CVE-2026-56746?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST