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CVE-2026-56820

7.4 · HIGH

Netty is a network application framework for development of protocol servers and clients.

Published Jul 21, 2026CWE-295EPSS 0.31%

Overview

CVE-2026-56820 is a high-severity vulnerability. It was published on July 21, 2026 and has a CVSS 3.1 base score of 7.4 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.4, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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 prior to 4.1.135.Final, `OcspClient` does not validate that the `CertificateID` in an OCSP response matches the requested `CertificateID`, which can lead to replay attack. `OcspClient.validateResponse` accepts a legitimately signed `GOOD` status response for an unrelated certificate issued by the same CA, allowing bypass of revocation checks for another certificate. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003bGitHubgithub.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6GitHubgithub.com/netty/netty/releases/tag/netty-4.1.136.FinalGitHubgithub.com/netty/netty/releases/tag/netty-4.2.16.FinalGitHubgithub.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg

How CyberStrike helps

Frequently asked questions

What is CVE-2026-56820?

CVE-2026-56820 is a high-severity vulnerability. It was published on July 21, 2026 and has a CVSS 3.1 base score of 7.4 (HIGH).

How severe is CVE-2026-56820?

This vulnerability has a CVSS 3.1 base score of 7.4, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-56820?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-56820?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-56820 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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