Netty up to 4.2.15 Http3FrameCodec decodeFrame payLoadLength resource consumption

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Netty up to 4.2.15. This affects the function decodeFrame of the component Http3FrameCodec. The manipulation of the argument payLoadLength leads to resource consumption. This vulnerability is referenced as CVE-2026-56816. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Netty up to 4.2.15 and classified as problematic. This issue affects the function decodeFrame of the component Http3FrameCodec. The manipulation of the argument payLoadLength with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-56816 since 06/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 4.2.16.Final eliminates this vulnerability.

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Productinfo

Name

• Netty

Version

• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5
• 4.2.6
• 4.2.7
• 4.2.8
• 4.2.9
• 4.2.10
• 4.2.11
• 4.2.12
• 4.2.13
• 4.2.14
• 4.2.15

Website

• Product: https://github.com/netty/netty/

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