CVE-2026-56816: 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

highCVSS 7.5CVE-2026-56816

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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.5
Published: 2026-07-21
Last updated: 2026-07-22
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-56816

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-568160.52% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 41% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-56816	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[NEW] [high] Netty: Multiple vulnerabilitiescert-bund
highGHSA-hpcc-26xq-25fv: Netty: Memory Exhaustion via HTTP/3 Reserved Frame Typesghsa

CVE-2026-56816: 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

Details

Exploitation outlook

Referenced CVEs

Same CVEs, other sources

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