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TI-2026-40969 Aliases CVE-2026-56816GHSA-hpcc-26xq-25fv

Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types

Priority MEDIUM 40CWE-400Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-400.

Summary

Netty is a network application framework for development of protocol servers and clients. Prior to 4.2.16.Final, Netty's `Http3FrameCodec` buffers incoming data for HTTP/3 reserved frame types up to the wire-specified payload length without limits; `decodeFrame` trusts `payLoadLength`, allowing an attacker to open multiple QUIC streams and send reserved frames with very large payload lengths to cause memory exhaustion and denial of service. This issue is fixed in version 4.2.16.Final.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00644 51st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed netty (netty): 4.2.16.Finalio.netty:netty-codec-http3 (Maven): 4.2.16.Final

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

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

Affected products

VendorProductAffected versionsFixed inStatusSource
nettynettybefore 4.2.16.Final4.2.16.FinalPatch availableCNA
—io.netty:netty-codec-http3 (Maven)before 4.2.16.Final4.2.16.FinalPatch availableGHSA-hpcc-26xq-25fv
  • netty Vendornetty Affected before 4.2.16.Final Fixed in 4.2.16.Final Patch available CNA
  • io.netty:netty-codec-http3 (Maven) Vendor— Affected before 4.2.16.Final Fixed in 4.2.16.Final Patch available GHSA-hpcc-26xq-25fv

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*4.2.2 to before 4.2.16Vulnerablenetty
  • cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions 4.2.2 to before 4.2.16 Vulnerable ·netty

Remediation

  • Fix · CNA netty (netty) Fixed in 4.2.16.Final
  • Fix · GHSA-hpcc-26xq-25fv io.netty:netty-codec-http3 (Maven) Fixed in 4.2.16.Final Advisory →

Vendor assessments

Red Hat

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

Not affected: 2 products
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift Dev Spaces

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-56816
  2. 2026-10-03 Alias added: GHSA-hpcc-26xq-25fv
  3. 2026-10-21 EPSS moved to the 50th–90th percentile

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • 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-2026-40973 Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks CVSS 3.1CRITICAL 9.1
  • TI-2026-40972 Uncontrolled resource consumption in netty 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