CVE-2021-45932Public exploit

Application crash via MQTT packet-type confusion

Published Dec 31, 2021 · Updated Aug 4, 2024

Heap-based buffer overflow in wolfSSL wolfMQTT 1.9 allows context-dependent attackers to crash an application via a crafted MQTT packet. MqttClient_WaitType treats unrelated packet types as equivalent when both fail its publish-response test, so MqttDecode_Publish receives the wrong heap-backed packet object and writes four bytes beyond its allocation. Exploitation requires an application to process the malformed packet, and the documented consequence is service interruption rather than data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in wolfSSL wolfMQTT 1.9 allows context-dependent attackers to crash an application via a crafted MQTT packet. MqttClient_WaitType treats unrelated packet types as equivalent when both fail its publish-response test, so MqttDecode_Publish receives the wrong heap-backed packet object and writes four bytes beyond its allocation. Exploitation requires an application to process the malformed packet, and the documented consequence is service interruption rather than data disclosure or modification.

The record

CVE
CVE-2021-45932
Published
Dec 31, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 31, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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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