Vulnerability · Published May 13, 2026 · Assigned by GitHub_M

CVE-2026-42583Netty: Lz4FrameDecoder resource exhaustion

High 7.5

In plain English

A high-severity uncontrolled resource consumption in netty-codec from io.netty. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 59.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	netty	no fix listed	DEBIAN-CVE-2026-42583
Debian:13	netty	no fix listed	DEBIAN-CVE-2026-42583
Debian:14	netty	no fix listed	DEBIAN-CVE-2026-42583
Maven	io.netty:netty-codec	4.1.133.Final	GHSA-mj4r-2hfc-f8p6
Maven	io.netty:netty-codec-compression	4.2.13.Final	GHSA-mj4r-2hfc-f8p6
Ubuntu:25.10	netty	no fix listed	UBUNTU-CVE-2026-42583

Affected products (as reported)

Vendor	Product	Versions
netty	netty	>= 4.2.0.Alpha1, < 4.2.13.Final< 4.1.133.Final
io.netty	netty-codec	< 4.1.133.Final
io.netty	netty-codec-compression	< 4.2.13.Final

Weakness: CWE-400, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/netty/netty/security/advisories/GHSA-mj4r-2hfc-f8p6 x_refsource_CONFIRM