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Meshtastic FirmwareOperating system · Meshtastic

CVE-2025-21608

MEDIUM · 5.3 CVSS v3.1 Published 2025-02-18
Fix available
A fix is available. Upgrade to 2.5.19 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges 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
Meshtastic is an open source mesh networking solution. In affected firmware versions crafted packets over MQTT are able to appear as a DM in client to a node even though they were not decoded with PKC. This issue has been addressed in version 2.5.19 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

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 · moderate confidence

In affected Meshtastic firmware versions, crafted MQTT packets can be manipulated to appear as Direct Messages (DMs) in the client interface even when they were not decoded using Private Key Cryptography (PKC). This allows an attacker to potentially inject fake private-looking messages, bypassing the expected encryption verification.

MitigationUpgrade Meshtastic firmware to version 2.5.19 or later to resolve this MQTT packet validation bypass. There are no viable workarounds; immediate patching is recommended given the CVSS 5.3 severity.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Meshtastic FirmwareOperating system
Affected:>= 2.5.0, < 2.5.19

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
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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 installed Meshtastic firmware version
    Access your Meshtastic device via CLI (meshtastic --get firmware_version) or check the device UI/system info screen to retrieve the current firmware version number
    Affected if The version is 2.5.0 or higher but lower than 2.5.19 (the device falls within the vulnerable range)
  2. Verify MQTT messaging is enabled
    Check the device configuration settings for MQTT client functionality - typically via meshtastic --get mqtt or through the device web interface/phone app settings under MQTT or Network settings
    Affected if MQTT is actively enabled and the device is connecting to an MQTT broker (the vulnerability exploits MQTT packet handling)
  3. Confirm Direct Message encryption configuration
    Inspect the device settings for Private Key Cryptography (PKC) or end-to-end encryption settings for direct messages - look for DM encryption mode, key configuration, or PKC-enabled status
    Affected if PKC is not enforced or is misconfigured for direct message reception, allowing the device to accept packets without proper PKC verification

You are affected if your Meshtastic firmware version is between 2.5.0 and 2.5.18 inclusive AND MQTT is enabled, as this combination allows the validation bypass to be exploited.

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
Upgrade available Upgrade to 2.5.19 or later
Fixed in 2.5.19
Interim mitigation

Upgrade Meshtastic firmware to version 2.5.19 or later to resolve this MQTT packet validation bypass. There are no viable workarounds; immediate patching is recommended given the CVSS 5.3 severity.

Recommended fix High confidence

2.5.19

  1. Identify all Meshtastic devices running firmware version 2.5.0 through 2.5.18
  2. Download Meshtastic firmware version 2.5.19 or later from the official Meshtastic releases repository
  3. Connect each Meshtastic device to a computer via USB
  4. Use the Meshtastic flashing tool or CLI to flash the updated firmware to each device
  5. Verify that the upgraded devices are running firmware version 2.5.19 or later
  6. Confirm that MQTT packets now properly require PKC decoding before displaying as direct messages

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

Fix this in Meshtastic Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2025-21608 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data