CVE-2026-56745: Netty [SpdyHttpDecoder] ByteBuf Reference Leak On Vulnerability

HIGH
Advisory Identifier: GHSA-jppx-w49h-x2qq
Share
CWE-400
Published
Advisory Summary

CVE-2026-56745 is a HIGH [spdyhttpdecoder] bytebuf reference leak on vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Netty libraries in the Maven ecosystem. The issue involves [spdyhttpdecoder] bytebuf reference leak on rst_stream leads to native memory exhaustion. Remediation is available by upgrading affected packages to version 4.2.16.Final, 4.1.136.Final.

CVE-2026-56745 at a Glance

CVE Identifier CVE-2026-56745
GHSA Identifier GHSA-jppx-w49h-x2qq
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Netty
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-56745

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-http fixed: 4.2.16.Final 
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-codec-http</artifactId>
    <version>4.2.16.Final</version>
</dependency>
io.netty:netty-codec-http fixed: 4.1.136.Final 
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-codec-http</artifactId>
    <version>4.1.136.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-2026-56745, 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 4.2.16.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-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. 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

The `SpdyHttpDecoder` handler in Netty's SPDY-to-HTTP codec allocates a pooled `ByteBuf` when processing a client-initiated `SYN_STREAM` frame with `FLAG_FIN=0`, storing the partially-constructed `FullHttpRequest` in an internal map (`messageMap`) to accumulate subsequent `DATA` frames. When the remote peer sends an `RST_STREAM` for that stream, or when the accumulated content exceeds `maxContentLength`, the decoder removes the entry from the map but **never releases the pooled ByteBuf**, permanently leaking the allocated memory.

CVE-2026-56745 Affected Netty Versions

2 component(s)
Fixed Versions:
4.2.16.Final4.1.136.Final
Product / Package Ecosystem Affected Versions Fixed Version
io.netty:netty-codec-http
maven/io.netty/netty-codec-http
Maven
≥ 4.2.0.Final
< 4.2.16.Final
4.2.16.Final
io.netty:netty-codec-http
maven/io.netty/netty-codec-http
Maven
≥ 4.1.0.Final
< 4.1.136.Final
4.1.136.Final

References

Netty Source Repository REPOSITORY
https://github.com/netty/netty
GitHub Advisory / Wiki ADVISORY
https://github.com/netty/netty/security/advisories/GHSA-jppx-w49h-x2qq
NVD — CVE-2026-56745 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56745
Security Fix Commit FIX COMMIT
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
Security Fix Commit FIX COMMIT
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
Netty Release RELEASE
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
Netty Release RELEASE
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final

Frequently Asked Questions

What is CVE-2026-56745?
CVE-2026-56745 is a security vulnerability in Netty involving [SpdyHttpDecoder] ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion under CWE-400: Uncontrolled Resource Consumption.
Which Netty versions are affected?
Affected versions include releases prior to 4.2.16.Final, 4.1.136.Final across affected packages: io.netty:netty-codec-http.
What version fixes CVE-2026-56745?
Upgrading to 4.2.16.Final, 4.1.136.Final (or the latest patched release for your respective branch) resolves the vulnerability.
Is netty-codec-http affected?
Yes, io.netty:netty-codec-http is affected in releases prior to 4.2.16.Final, 4.1.136.Final. Upgrade your dependency to 4.2.16.Final, 4.1.136.Final or later.
What CWE is associated with CVE-2026-56745?
CVE-2026-56745 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check Maven dependencies for CVE-2026-56745?
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-jppx-w49h-x2qq",
  "modified" : "2026-07-22T21:32:24Z",
  "published" : "2026-07-22T21:32:24Z",
  "aliases" : [ "CVE-2026-56745" ],
  "summary" : "Netty: [SpdyHttpDecoder] ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion",
  "details" : "The `SpdyHttpDecoder` handler in Netty's SPDY-to-HTTP codec allocates a pooled `ByteBuf` when processing a client-initiated `SYN_STREAM` frame with `FLAG_FIN=0`, storing the partially-constructed `FullHttpRequest` in an internal map (`messageMap`) to accumulate subsequent `DATA` frames. When the remote peer sends an `RST_STREAM` for that stream, or when the accumulated content exceeds `maxContentLength`, the decoder removes the entry from the map but **never releases the pooled ByteBuf**, permanently leaking the allocated memory.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-http"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0.Final"
      }, {
        "fixed" : "4.2.16.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.2.15.Final"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-http"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.1.0.Final"
      }, {
        "fixed" : "4.1.136.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.135.Final"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/security/advisories/GHSA-jppx-w49h-x2qq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-56745"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/netty/netty"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-22T21:32:24Z",
    "nvd_published_at" : "2026-07-21T22:17:14Z"
  }
}