CVE-2024-31040Public exploitNetwork attack vector

Broker crash via out-of-bounds variable-integer read

Published Apr 17, 2024 · Updated Aug 2, 2024

Heap buffer overflow in NanoMQ 0.21.7 allows remote attackers to crash the MQTT broker via crafted network hexstreams. The get_var_integer function in mqtt_parser.c continues parsing beyond a 14-byte heap buffer and reads one byte past the allocation. The published reproduction sends the crafted sequence to the MQTT TCP listener and terminates the broker process, interrupting its messaging service.

CVSS severity2.7
Low
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in NanoMQ 0.21.7 allows remote attackers to crash the MQTT broker via crafted network hexstreams. The get_var_integer function in mqtt_parser.c continues parsing beyond a 14-byte heap buffer and reads one byte past the allocation. The published reproduction sends the crafted sequence to the MQTT TCP listener and terminates the broker process, interrupting its messaging service.

The record

CVE
CVE-2024-31040
Published
Apr 17, 2024
Updated
Aug 2, 2024
Vendor
EMQ Technologies
Product
NanoMQ
Classifications
CWE-120, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 17, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record 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=0.21.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

EMQ Technologies · NanoMQversion=0.21.7

Published CVSS scores

2.7CISA ADPCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

Public exploit references

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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