Memory Leak in Netty HAProxy Decoder

Compliance Impact

The vulnerability CVE-2026-44893 causes a memory leak due to an unreleased buffer slice when processing malformed HAProxy SSL TLV data, potentially leading to denial of service by impacting availability.

While the CVE description and resources highlight the impact on system availability, there is no direct information on how this vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.

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Executive Summary

The vulnerability CVE-2026-44893 affects the Netty library's HAProxy SSL TLV parsing mechanism. When decoding a PP2_TYPE_SSL TLV, the function HAProxyMessage.readNextTLV() creates a retained slice of the buffer based on the specified length. If an attacker sets the TLV length below 5 bytes, subsequent read operations throw an IndexOutOfBoundsException. Because the decoder only catches specific exceptions, this exception propagates and causes the retained slice on the pooled cumulation buffer to never be released, leading to a memory leak.

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Impact Analysis

This vulnerability can impact you by causing a memory leak in applications using affected versions of the Netty library. The memory leak occurs because the retained slice on the pooled cumulation buffer is never released when the exception is thrown. Over time, this can degrade application performance or cause it to crash due to resource exhaustion, impacting availability.

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade the Netty library to a patched version. Specifically, update to version 4.2.15.Final or later, or 4.1.135.Final or later, where the issue has been fixed.

These versions address the problem by properly handling the TLV length and preventing the IndexOutOfBoundsException and associated memory leak.

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Detection Guidance

This vulnerability affects specific versions of the Netty library's HAProxy SSL TLV parsing mechanism, particularly versions 4.2.0.Final to 4.2.14.Final and 4.1.134.Final or earlier. Detection involves identifying if these vulnerable versions of Netty are in use on your systems.

To detect the vulnerability on your system, you should check the version of the Netty library deployed in your applications or services. This can often be done by inspecting dependency manifests or using package management tools.

• For Java applications using Maven, run: mvn dependency:tree | grep netty
• For Gradle projects, run: ./gradlew dependencies | grep netty
• If you have access to the deployed JAR files, you can check the version by inspecting the JAR manifest or file names, e.g., using: unzip -p netty-codec-haproxy-*.jar META-INF/MANIFEST.MF | grep Implementation-Version

Network detection of exploitation attempts may be difficult because the issue arises from malformed PP2_TYPE_SSL TLVs with length below 5 bytes causing an exception. Monitoring application logs for IndexOutOfBoundsException or memory leaks related to HAProxyMessageDecoder could indicate exploitation attempts.

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