CVE-2023-33657Public exploitNetwork attack vector

Broker crash via retained-message data race

Published Jun 8, 2023 · Updated Jan 6, 2025

Use-after-free in NanoMQ 0.17.2 allows remote attackers to crash the MQTT broker by repeatedly sending malformed publish packets. The nni_mqtt_msg_get_publish_property() path in mqtt_msg.c reads retained-message properties while broker concurrency can free shared message storage; the patch clones retained messages to prevent that race. Triggering requires network access to the MQTT listener and repeated malformed packets, with the upstream reproducer reporting a crash after 2 to 15 replays.

CVSS severity7.5
High
EPSS probability0.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in NanoMQ 0.17.2 allows remote attackers to crash the MQTT broker by repeatedly sending malformed publish packets. The nni_mqtt_msg_get_publish_property() path in mqtt_msg.c reads retained-message properties while broker concurrency can free shared message storage; the patch clones retained messages to prevent that race. Triggering requires network access to the MQTT listener and repeated malformed packets, with the upstream reproducer reporting a crash after 2 to 15 replays.

The record

CVE
CVE-2023-33657
Published
Jun 8, 2023
Updated
Jan 6, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1499.004
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

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
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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