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Use After FreeWeakness · CWE-416

CVE-2025-65953

MEDIUM · 6.0 CVSS v4.0 Published 2025-11-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
66/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. Prior to version 0.22.5, a Heap-Use-After-Free (UAF) vulnerability exists in the TCP transport component of NanoMQ, which relies on the underlying NanoNNG library (specifically in src/sp/transport/mqtt/broker_tcp.c). The vulnerability is due to improper resource management and premature cleanup of message and pipe structures under specific malformed MQTTV5 retain message traffic conditions. This issue has been patched in version 0.22.5.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A Heap Use-After-Free vulnerability exists in the TCP transport component of NanoMQ MQTT Broker (src/sp/transport/mqtt/broker_tcp.c) due to improper resource management and premature cleanup of message and pipe structures when processing specific malformed MQTTv5 retain messages. An attacker sending specially crafted retain messages can cause the broker to access freed memory, potentially leading to denial of service or arbitrary code execution.

MitigationUpgrade NanoMQ to version 0.22.5 or later which contains the patch for this vulnerability. If immediate upgrading is not feasible, consider network-level filtering of malformed MQTTv5 retain messages as a temporary workaround.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify NanoMQ installation and version
    Run 'nanomq --version' or check the broker startup logs for the version number
    Affected if The installed version is earlier than 0.22.5 (e.g., 0.22.4, 0.21.x, etc.)
  2. Confirm TCP transport is in use
    Inspect the NanoMQ configuration file (nanomq.conf) or running process arguments for 'tcp' or 'mqtt-tcp' listener settings
    Affected if TCP transport listeners are configured and active (this is the default transport mode)
  3. Verify MQTTv5 protocol support is enabled
    Check nanomq.conf for 'mqtt_version=5' or inspect broker logs for 'MQTTv5' protocol initialization messages
    Affected if MQTTv5 support is enabled (the vulnerability affects MQTTv5 retain message handling specifically)
  4. Confirm retain message processing is active
    Check the broker configuration or logs for retain message handling settings; inspect any running retain store configurations
    Affected if Retain message processing is enabled (retain messages are stored and delivered by the broker)

The environment is affected if NanoMQ versions earlier than 0.22.5 are running with TCP transport and MQTTv5 retain message processing enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade NanoMQ to version 0.22.5 or later which contains the patch for this vulnerability. If immediate upgrading is not feasible, consider network-level filtering of malformed MQTTv5 retain messages as a temporary workaround.

Recommended fix High confidence

0.22.5

  1. 1. Identify the current NanoMQ version by running 'nanomq version' or checking the package manager
  2. 2. Stop the NanoMQ service if running (e.g., 'systemctl stop nanomq' or 'nanomq stop')
  3. 3. Back up the NanoMQ configuration files (typically in /etc/nanomq/ or the config directory)
  4. 4. Upgrade NanoMQ to version 0.22.5 using the appropriate package manager or build from source
  5. 5. Verify the installation by checking 'nanomq version' shows 0.22.5
  6. 6. Restore the configuration files from the backup
  7. 7. Start the NanoMQ service and verify it runs correctly

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-65953 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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