io.netty/netty-handler-ssl-ocsp: Netty: Certificate revocation bypass via OCSP response replay attack (CVE-2026-56820)

Overview

A flaw was found in Netty. The OcspClient component fails to validate that the Certificate ID in an Online Certificate Status Protocol (OCSP) response matches the requested Certificate ID. This vulnerability allows a remote attacker to bypass certificate revocation checks by presenting a legitimately signed OCSP response for an unrelated certificate issued by the same Certificate Authority, leading to a replay attack. This can result in the acceptance of revoked certificates, potentially compromising the integrity and confidentiality of communications.

Vendor advisories

• RHSA-2026:69296 · Red Hat · fixed in: Red Hat Data Grid 8.6.3 · released 2026-09-21 · advisory
• RHSA-2026:54622 · Red Hat · fixed in: Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16 · released 2026-08-13 · advisory

io.netty/netty-handler-ssl-ocsp: Netty: Certificate revocation bypass via OCSP response replay attack — rated Important by Red Hat. Released 2026-07-21, updated 2026-09-21.

Fixed:

• Red Hat Data Grid 8.6.3
• Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16

Not affected:

• Red Hat JBoss Enterprise Application Platform Expansion Pack

Remediation

Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to: https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:69296 Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:54622

Workarounds / mitigations:

• 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.

Package advisory (CVE-2026-56820)

Affected packages:

• io.netty:netty-handler-ssl-ocsp >= 4.2.0.Final, < 4.2.16.Final
• io.netty:netty-handler-ssl-ocsp < 4.1.136.Final

Patched in:

• io.netty:netty-handler-ssl-ocsp 4.2.16.Final
• io.netty:netty-handler-ssl-ocsp 4.1.136.Final

Source: https://github.com/advisories/GHSA-272m-gcwp-mpwg