Description
Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.
Published: 2026-07-28
Score: 7.4 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-g7hg-vrcf-mvmr Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator
History

Tue, 28 Jul 2026 23:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in netty-handler-ssl-ocsp, a component of the Netty network application framework. The Online Certificate Status Protocol (OCSP) stapling validator in this component does not properly check certificate revocation status. This can allow an attacker to use revoked certificates without detection, potentially compromising secure communications. Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.
Title io.netty/netty-handler-ssl-ocsp: Netty: Improper certificate revocation check in netty-handler-ssl-ocsp Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator
Weaknesses CWE-299
References
Metrics cvssV3_1

{'score': 5.7, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'}

 cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Tue, 28 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in netty-handler-ssl-ocsp, a component of the Netty network application framework. The Online Certificate Status Protocol (OCSP) stapling validator in this component does not properly check certificate revocation status. This can allow an attacker to use revoked certificates without detection, potentially compromising secure communications.
Title io.netty/netty-handler-ssl-ocsp: Netty: Improper certificate revocation check in netty-handler-ssl-ocsp
Weaknesses CWE-93
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.7, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'}

threat_severity

Moderate

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-28T23:07:13.616Z

Reserved: 2026-06-23T14:55:09.116Z

Link: CVE-2026-56821

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-07-09T00:00:00Z

Links: CVE-2026-56821 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-299

    Improper Check for Certificate Revocation

  • CWE-93

    Improper Neutralization of CRLF Sequences ('CRLF Injection')