CVE-2026-44248Network attack vector

Service interruption via unbounded MQTT property decoding

Published May 13, 2026 · Updated May 13, 2026

Resource exhaustion in Netty before 4.1.133.Final and 4.2.0.Alpha1 through 4.2.12.Final allows remote attackers to interrupt MQTT services. MqttDecoder calls decodeVariableHeader() and decodeProperties() before enforcing maxBytesInMessage, while ReplayingDecoder repeatedly reparses and buffers oversized Properties data. An unauthenticated network peer must reach an application using the MQTT 5 decoder; CPU and memory consumption can leave its event loop unresponsive.

CVSS severity5.3
Medium
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Netty before 4.1.133.Final and 4.2.0.Alpha1 through 4.2.12.Final allows remote attackers to interrupt MQTT services. MqttDecoder calls decodeVariableHeader() and decodeProperties() before enforcing maxBytesInMessage, while ReplayingDecoder repeatedly reparses and buffers oversized Properties data. An unauthenticated network peer must reach an application using the MQTT 5 decoder; CPU and memory consumption can leave its event loop unresponsive.

The record

CVE
CVE-2026-44248
Published
May 13, 2026
Updated
May 13, 2026
Vendor
The Netty Project
Product
netty-codec-mqtt
Classifications
CWE-400, CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.1.133.Final
  2. Affected versionversion=>= 4.2.0.Alpha1, < 4.2.13.Final

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Netty Project · netty-codec-mqttversion=< 4.1.133.Final; version=>= 4.2.0.Alpha1, < 4.2.13.Final
The Netty Project · Nettyversion=< 4.1.133.Final; version=>= 4.2.0.Alpha1, < 4.2.13.Final

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
7.5redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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