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Advisory severityMedium5.7Red Hat Linux

Medium [CVE-2026-56821] Improper certificate revocation check in netty-handler-ssl-ocsp

This medium-severity Red Hat Linux advisory covers CVE-2026-56821 affecting Red Hat build of Apache Camel for Spring Boot 4, Red Hat Data Grid 8, Red Hat JBoss Enterprise Application Platform Expansion Pack.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-56821 Source published Source updated

VulniPulse record published Record updated

CVE-2026-56821
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

Summary

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Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response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.

Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. 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.

Red Hat severity: Moderate — CVSS 5.7 (CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N). Weakness: CWE-93.

Affected Red Hat products: Red Hat build of Apache Camel for Spring Boot 4; Red Hat Data Grid 8; Red Hat JBoss Enterprise Application Platform Expansion Pack. Red Hat does not currently list a fixing RHSA for this CVE.

Is CVE-2026-56821 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-56821 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-56821?

Upgrade to a fixed release named by Red Hat:

  • 4.1.136
  • 4.2.16

Confirm against the vendor advisory before you patch.

Affected versions
  • < 4.1.136.Final
  • < 4.2.16.Final

Official advisory · high-confidence parse· fetched 3 days ago·verify at source

Fixed versions
  • 4.1.136
  • 4.2.16

Official advisory · high-confidence parse· fetched 3 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Official advisory · high-confidence parse· fetched 3 days ago·verify at source

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