CVE-2026-42583

High

Description

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.

SeverityHigh

CVSS7.5

Exploit probability—

ProductNetty

PublishedMay 13, 2026

First seenMay 13, 2026

Weakness typeCWE-400Uncontrolled resource consumption CWE-770Allocation of resources without limits

How to fix

Update

netty netty4.1.133, 4.2.13 or later
io.netty:netty-codec-compression4.2.13.Final or later
io.netty:netty-codec4.1.133.Final or later

Affected products

Product	Affected versions	Fixed in
netty netty	v < 4.1.133, 4.2.0 ≤ v < 4.2.13	4.1.133, 4.2.13
io.netty:netty-codec-compressionMaven	v < 4.2.13.Final	4.2.13.Final
io.netty:netty-codecMaven	v < 4.1.133.Final	4.1.133.Final

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