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TI-2026-40973 Aliases CVE-2026-56820GHSA-272m-gcwp-mpwg

Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks

Priority HIGH 74CWE-295Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Spoofing
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-295.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00313 24th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed netty (netty): 4.2.16.Final, 4.1.136.Finalio.netty:netty-handler-ssl-ocsp (Maven): 4.2.16.Final, 4.1.136.FinalRed Hat: 2 advisories

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nettynetty4.2.0.Final to before 4.2.16.Final; before 4.1.136.Final4.2.16.Final, 4.1.136.FinalPatch availableCNA
—io.netty:netty-handler-ssl-ocsp (Maven)4.2.0.Final to before 4.2.16.Final4.2.16.FinalPatch availableGHSA-272m-gcwp-mpwg
—io.netty:netty-handler-ssl-ocsp (Maven)before 4.1.136.Final4.1.136.FinalPatch availableGHSA-272m-gcwp-mpwg
  • netty Vendornetty Affected 4.2.0.Final to before 4.2.16.Final; before 4.1.136.Final Fixed in 4.2.16.Final, 4.1.136.Final Patch available CNA
  • io.netty:netty-handler-ssl-ocsp (Maven) Vendor— Affected 4.2.0.Final to before 4.2.16.Final Fixed in 4.2.16.Final Patch available GHSA-272m-gcwp-mpwg
  • io.netty:netty-handler-ssl-ocsp (Maven) Vendor— Affected before 4.1.136.Final Fixed in 4.1.136.Final Patch available GHSA-272m-gcwp-mpwg

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*before 4.1.136; 4.2.0 to before 4.2.16Vulnerablenetty
  • cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions before 4.1.136; 4.2.0 to before 4.2.16 Vulnerable ·netty

Remediation

  • Fix · CNA netty (netty) Fixed in 4.2.16.Final, 4.1.136.Final
  • Fix · GHSA-272m-gcwp-mpwg io.netty:netty-handler-ssl-ocsp (Maven) Fixed in 4.2.16.Final Advisory →
  • Fix · GHSA-272m-gcwp-mpwg io.netty:netty-handler-ssl-ocsp (Maven) Fixed in 4.1.136.Final Advisory →

Red Hat 2 advisories

  • RHSA-2026:69296 Released 2026-09-21 · Red Hat rating Important
    Red Hat Data Grid 8.6.3 security update
    • Red Hat Data Grid 8.6.3
  • RHSA-2026:54622 Released 2026-08-13 · Red Hat rating Important
    Red Hat Build of Apache Camel 4.18.3 for Spring Boot release.
    • Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Data Grid 8.6.3Fixed RHSA-2026:69296
Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16Fixed RHSA-2026:54622
Not affected: 1 product
  • Red Hat JBoss Enterprise Application Platform Expansion Pack

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-56820
  2. 2026-10-03 Alias added: GHSA-272m-gcwp-mpwg

References

Exploit 1

Patch 2

Advisory 1

Other 3

  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2026-30861 Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization CVSS 3.1CRITICAL 9.8
  • TI-2026-30864 Netty: HttpClientCodec response desynchronization CVSS 3.1CRITICAL 9.1
  • TI-2026-30859 Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) CVSS 3.1CRITICAL 9.1
  • TI-2026-40972 Uncontrolled resource consumption in netty CVSS 3.1HIGH 7.5
  • TI-2026-40298 Netty SPDY SETTINGS frame count materializes unbounded settings map CVSS 3.1HIGH 7.5
See all 92 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences