CVE-2026-56816

Netty: Memory Exhaustion via HTTP/3 Reserved Frame Types

HIGH
7.5
CVSS Score
Published: July 21, 2026 at 09:56 PM UTC
Updated: August 7, 2026 at 08:47 PM UTC
1 product affected across 1 vendorNetty

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Severity
HIGH7.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.2.16.Final4.2.2 ≤ v < 4.2.16
Affected range stops below 4.2.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2.16.Final, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/netty/netty/security/advisories/GHSA-hpcc-26xq-25fv
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400

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