CVE-2026-56816
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductNetty
PublishedJul 21, 2026
First seenJul 21, 2026
Weakness typeCWE-400Uncontrolled resource consumption
How to fix
Update
- netty netty4.2.16 or later
- io.netty:netty-codec-http34.2.16.Final or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| netty netty | 4.2.2 ≤ v < 4.2.16 | 4.2.16 |
| io.netty:netty-codec-http3Maven | v < 4.2.16.Final | 4.2.16.Final |
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