Io.netty:netty codec http2: netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion (CVE-2026-48043)
### Impact The `DelegatingDecompressorFrameListener` class orchestrates HTTP/2 decompression by embedding a per-stream `EmbeddedChannel` that runs the appropriate decompression codec (gzip, deflate, zstd) and forwards decompressed chunks to a wrapped listener. Each decompressed chunk is a pooled `ByteBuf` handed to an anonymous `ChannelInboundHandlerAdapter` tail handler, which becomes the sole owner responsible for releasing it. A remote peer could send frames that would result in the flow-controller throwing and so trigger a resource leak which at the end might take down the whole JVM due OOME.
AI Analysis
Technical Summary
The vulnerability in io.netty:netty-codec-http2 (CVE-2026-48043) involves a ByteBuf reference-count leak in the DelegatingDecompressorFrameListener class. This class manages HTTP/2 decompression by using an EmbeddedChannel per stream to run decompression codecs and forward decompressed chunks. When a remote peer sends frames that cause the flow-controller to throw exceptions, the ByteBuf objects are not properly released, resulting in a resource leak. Over time, this leak can exhaust memory resources, leading to an Out Of Memory Error and potentially crashing the JVM, causing a denial of service. The flaw affects versions prior to 4.1.135.Final and versions from 4.2.0.Alpha1 up to 4.2.15.Final. Red Hat has classified this as an important denial of service vulnerability and has released patches in netty versions 4.1.135.Final and 4.2.15.Final to fix the issue.
Potential Impact
The vulnerability can be exploited remotely without authentication. It causes a resource leak that leads to memory exhaustion and an Out Of Memory Error, which can crash the Java Virtual Machine and cause a denial of service. There is no impact on confidentiality or integrity reported. The CVSS 3.1 base score is 5.3 (medium severity) with an attack vector of network, low attack complexity, no privileges required, and no user interaction needed.
Mitigation Recommendations
A patch is available and should be applied to upgrade to netty-codec-http2 versions 4.1.135.Final or later, or 4.2.15.Final or later. Red Hat has released security advisories and errata with updates addressing this vulnerability. No other mitigations are currently available or meet Red Hat's criteria for ease of use and applicability. Users should prioritize applying the official fixes to prevent potential denial of service.
Io.netty:netty codec http2: netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion (CVE-2026-48043)
Description
### Impact The `DelegatingDecompressorFrameListener` class orchestrates HTTP/2 decompression by embedding a per-stream `EmbeddedChannel` that runs the appropriate decompression codec (gzip, deflate, zstd) and forwards decompressed chunks to a wrapped listener. Each decompressed chunk is a pooled `ByteBuf` handed to an anonymous `ChannelInboundHandlerAdapter` tail handler, which becomes the sole owner responsible for releasing it. A remote peer could send frames that would result in the flow-controller throwing and so trigger a resource leak which at the end might take down the whole JVM due OOME.
CVSS v3.1
Score 5.3medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in io.netty:netty-codec-http2 (CVE-2026-48043) involves a ByteBuf reference-count leak in the DelegatingDecompressorFrameListener class. This class manages HTTP/2 decompression by using an EmbeddedChannel per stream to run decompression codecs and forward decompressed chunks. When a remote peer sends frames that cause the flow-controller to throw exceptions, the ByteBuf objects are not properly released, resulting in a resource leak. Over time, this leak can exhaust memory resources, leading to an Out Of Memory Error and potentially crashing the JVM, causing a denial of service. The flaw affects versions prior to 4.1.135.Final and versions from 4.2.0.Alpha1 up to 4.2.15.Final. Red Hat has classified this as an important denial of service vulnerability and has released patches in netty versions 4.1.135.Final and 4.2.15.Final to fix the issue.
Potential Impact
The vulnerability can be exploited remotely without authentication. It causes a resource leak that leads to memory exhaustion and an Out Of Memory Error, which can crash the Java Virtual Machine and cause a denial of service. There is no impact on confidentiality or integrity reported. The CVSS 3.1 base score is 5.3 (medium severity) with an attack vector of network, low attack complexity, no privileges required, and no user interaction needed.
Mitigation Recommendations
A patch is available and should be applied to upgrade to netty-codec-http2 versions 4.1.135.Final or later, or 4.2.15.Final or later. Red Hat has released security advisories and errata with updates addressing this vulnerability. No other mitigations are currently available or meet Red Hat's criteria for ease of use and applicability. Users should prioritize applying the official fixes to prevent potential denial of service.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-c2gf-v879-257j
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-48043"]
- Ecosystems
- ["Maven"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6a50babc68715ace43586a1f
Added to database: 07/10/2026, 09:26:20 UTC
Last enriched: 08/12/2026, 18:03:13 UTC
Last updated: 09/14/2026, 10:01:31 UTC
Views: 100
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