High 7.5Published May 13, 2026

CVE-2026-42583Netty: Lz4FrameDecoder resource exhaustion

Updated under an hour ago (Oct 26, 2026, 5:00 PM ET)

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It affects netty and 2 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Lz4FrameDecoder allocates a ByteBuf of size decompressedLength (up to 32 MB per block) before LZ4 runs. A peer only needs a 21-byte header plus compressedLength payload bytes - 22 bytes if compressedLength == 1 - to force that allocation. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-400, CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

netty netty netty:netty (from the name)	from 4.2.0.Alpha1, < 4.2.13.Final; before 4.1.133.Final	CNA record
io.netty netty-codec io.netty:netty_codec (from the name)	before 4.1.133.Final	CNA record
io.netty netty-codec-compression io.netty:netty_codec_compression (from the name)	before 4.2.13.Final	CNA record
netty netty netty:netty	before 4.1.133; from 4.2.0 before 4.2.13	NVD

References

References

https://github.com/netty/netty/security/advisories/GHSA-mj4r-2hfc-f8p6	x-refsource-confirm, exploit, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.