Vulnerabilities in pkg:maven/io.netty/netty-codec-mqtt
PACKAGECVE-2026-44248 is a MODERATE (CVSS 5.3) remote code execution vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Netty MQTT libraries in the Maven ecosystem. The issue involves resource exhaustion in mqttdecoder. Remediation is available by upgrading affected packages to version 4.2.13.Final, 4.1.133.Final.
pkg:maven/io.netty/netty-codec-mqtt
Vulnerability advisories affecting package pkg:maven/io.netty/netty-codec-mqtt. Select an advisory below to view technical details or fixes.
| Advisory ID | CVE / NVD | Severity | Summary |
|---|---|---|---|
| GHSA-jfg9-48mv-9qgx | CVE-2026-44248 | MODERATE | Netty MQTT: Resource exhaustion in MqttDecoder |
CVE-2026-44248 at a Glance
Security Impact
CVSS: 5.3
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:L).
How to Fix CVE-2026-44248
To remediate this vulnerability, upgrade all affected Netty MQTT dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-codec-mqtt</artifactId>
<version>4.2.13.Final</version>
</dependency><dependency>
<groupId>io.netty</groupId>
<artifactId>netty-codec-mqtt</artifactId>
<version>4.1.133.Final</version>
</dependency>Run the following command in your project directory to verify that all resolved dependencies use the patched release:
mvn dependency:tree -Dincludes=io.nettyHow to Check if You Are Affected
To determine whether your Java application is affected by CVE-2026-44248, inspect your build dependencies using the Maven Dependency Plugin:
mvn dependency:tree -Dincludes=io.nettyAnalyze the terminal output to locate any version of Netty MQTT in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.13.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 MQTT, 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
CVE-2026-44248 Affected Netty MQTT Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
io.netty:netty-codec-mqtt
|
Maven |
≥ 4.2.0.Alpha1
< 4.2.13.Final
|
4.2.13.Final
|
|
io.netty:netty-codec-mqtt
|
Maven |
< 4.1.133.Final
|
4.1.133.Final
|
References
Frequently Asked Questions
What is CVE-2026-44248?
Which Netty MQTT versions are affected?
What version fixes CVE-2026-44248?
Is netty-codec-mqtt affected?
What is the CVSS score of CVE-2026-44248?
What CWE is associated with CVE-2026-44248?
How can I check Maven dependencies for CVE-2026-44248?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-jfg9-48mv-9qgx",
"modified" : "2026-05-14T20:41:33Z",
"published" : "2026-05-07T05:14:14Z",
"aliases" : [ "CVE-2026-44248" ],
"summary" : "Netty MQTT: Resource exhaustion in MqttDecoder",
"details" : "### Impact\nThe MQTT 5 header Properties section is parsed and buffered _before_ any message size limit is applied.\n\nSpecifically, in `MqttDecoder`, the `decodeVariableHeader()` method is called before the `bytesRemainingBeforeVariableHeader > maxBytesInMessage` check. The `decodeVariableHeader()` can call other methods which will call `decodeProperties()`. Effectively, Netty does not apply any limits to the size of the properties being decoded.\n\nAdditionally, because `MqttDecoder` extends `ReplayingDecoder`, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion.\n\nThis can cause high resource usage in both CPU and memory.\n\n### Resources\n`ANT-2026-09608`\nhttps://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Maven",
"name" : "io.netty:netty-codec-mqtt"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "4.2.0.Alpha1"
}, {
"fixed" : "4.2.13.Final"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 4.2.12.Final"
}
}, {
"package" : {
"ecosystem" : "Maven",
"name" : "io.netty:netty-codec-mqtt"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "4.1.133.Final"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 4.1.132.Final"
}
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/netty/netty/security/advisories/GHSA-jfg9-48mv-9qgx"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44248"
}, {
"type" : "WEB",
"url" : "https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/netty/netty"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-400" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2026-05-07T05:14:14Z",
"nvd_published_at" : "2026-05-13T19:17:27Z"
}
}