CVE-2023-33660Network attack vector

Broker crash via unchecked MQTT string length

Published Jun 8, 2023 · Updated Jan 6, 2025

Heap buffer overflow in NanoMQ 0.17.2 allows remote attackers to crash the MQTT broker by sending a malformed MQTT packet. The copyn_str function in mqtt_parser.c reads the two-byte MQTT string-length field without first rejecting an input buffer shorter than two bytes, allowing parsing to proceed past the buffer boundary. No authentication or user interaction is required; a malformed packet sent to the MQTT listener can terminate the broker and interrupt messaging.

CVSS severity7.5
High
EPSS probability1.20%
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 0.17.2 allows remote attackers to crash the MQTT broker by sending a malformed MQTT packet. The copyn_str function in mqtt_parser.c reads the two-byte MQTT string-length field without first rejecting an input buffer shorter than two bytes, allowing parsing to proceed past the buffer boundary. No authentication or user interaction is required; a malformed packet sent to the MQTT listener can terminate the broker and interrupt messaging.

The record

CVE
CVE-2023-33660
Published
Jun 8, 2023
Updated
Jan 6, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS: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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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