CVE-2026-44893: Netty HAProxy SSL TLV Parsing Leaks Vulnerability

HIGH
Advisory Identifier: GHSA-cc37-9q2j-3hfv
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CVSS 7.5
CWE-703
Published
Advisory Summary

CVE-2026-44893 is a HIGH (CVSS 7.5) haproxy ssl tlv parsing leaks vulnerability (CWE-703: Improper Check or Handling of Exceptional Conditions) affecting Netty libraries in the Maven ecosystem. The issue involves haproxy ssl tlv parsing leaks retained slice on invalid tlv length. Remediation is available by upgrading affected packages to version 4.2.15.Final, 4.1.135.Final.

CVE-2026-44893 at a Glance

CVE Identifier CVE-2026-44893
GHSA Identifier GHSA-cc37-9q2j-3hfv
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-703: Improper Check or Handling of Exceptional Conditions
Affected Product Netty
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-44893

To remediate this vulnerability, upgrade all affected Netty dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

io.netty:netty-codec-haproxy fixed: 4.2.15.Final 
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-codec-haproxy</artifactId>
    <version>4.2.15.Final</version>
</dependency>
io.netty:netty-codec-haproxy fixed: 4.1.135.Final 
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-codec-haproxy</artifactId>
    <version>4.1.135.Final</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=io.netty

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-44893, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=io.netty

Analyze the terminal output to locate any version of Netty in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.15.Final), your application is affected.

Note: The mvn dependency:tree -Dincludes=io.netty command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-703: Improper Check or Handling of Exceptional Conditions, where the product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product. In Netty, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

When decoding a PP2_TYPE_SSL TLV, HAProxyMessage.readNextTLV() first calls `header.retainedSlice(header.readerIndex(), length)` and only then reads the 1-byte client field and 4-byte verify field. If the attacker sets the TLV length below 5, the subsequent readByte/readInt throws IndexOutOfBoundsException. HAProxyMessageDecoder only catches HAProxyProtocolException around this call, so the IOOBE propagates and the retained slice on the pooled cumulation buffer is never released.

CVE-2026-44893 Affected Netty Versions

2 component(s)
Fixed Versions:
4.2.15.Final4.1.135.Final
Product / Package Ecosystem Affected Versions Fixed Version
io.netty:netty-codec-haproxy
maven/io.netty/netty-codec-haproxy
Maven
≥ 4.2.0.Final
< 4.2.15.Final
4.2.15.Final
io.netty:netty-codec-haproxy
maven/io.netty/netty-codec-haproxy
Maven
< 4.1.135.Final
4.1.135.Final

References

GitHub Advisory / Wiki ADVISORY
https://github.com/netty/netty/security/advisories/GHSA-cc37-9q2j-3hfv
NVD — CVE-2026-44893 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44893
Netty Source Repository REPOSITORY
https://github.com/netty/netty
Netty Release RELEASE
https://github.com/netty/netty/releases/tag/netty-4.1.135.Final
Netty Release RELEASE
https://github.com/netty/netty/releases/tag/netty-4.2.15.Final

Frequently Asked Questions

What is CVE-2026-44893?
CVE-2026-44893 is a security vulnerability in Netty involving HAProxy SSL TLV parsing leaks retained slice on invalid TLV length under CWE-703: Improper Check or Handling of Exceptional Conditions.
Which Netty versions are affected?
Affected versions include releases prior to 4.2.15.Final, 4.1.135.Final across affected packages: io.netty:netty-codec-haproxy.
What version fixes CVE-2026-44893?
Upgrading to 4.2.15.Final, 4.1.135.Final (or the latest patched release for your respective branch) resolves the vulnerability.
Is netty-codec-haproxy affected?
Yes, io.netty:netty-codec-haproxy is affected in releases prior to 4.2.15.Final, 4.1.135.Final. Upgrade your dependency to 4.2.15.Final, 4.1.135.Final or later.
What is the CVSS score of CVE-2026-44893?
CVE-2026-44893 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-44893?
CVE-2026-44893 is classified under CWE-703: Improper Check or Handling of Exceptional Conditions (The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.).
How can I check Maven dependencies for CVE-2026-44893?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=io.netty'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cc37-9q2j-3hfv",
  "modified" : "2026-06-12T19:29:14Z",
  "published" : "2026-06-08T19:02:21Z",
  "aliases" : [ "CVE-2026-44893" ],
  "summary" : "Netty: HAProxy SSL TLV parsing leaks retained slice on invalid TLV length",
  "details" : "When decoding a PP2_TYPE_SSL TLV, HAProxyMessage.readNextTLV() first calls `header.retainedSlice(header.readerIndex(), length)` and only then reads the 1-byte client field and 4-byte verify field. If the attacker sets the TLV length below 5, the subsequent readByte/readInt throws IndexOutOfBoundsException. HAProxyMessageDecoder only catches HAProxyProtocolException around this call, so the IOOBE propagates and the retained slice on the pooled cumulation buffer is never released.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-haproxy"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0.Final"
      }, {
        "fixed" : "4.2.15.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.2.14.Final"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-haproxy"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.135.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.134.Final"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/security/advisories/GHSA-cc37-9q2j-3hfv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44893"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/netty/netty"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/releases/tag/netty-4.1.135.Final"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-703" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-08T19:02:21Z",
    "nvd_published_at" : "2026-06-12T15:16:26Z"
  }
}