CVE-2025-21608 Forged packets over MQTT can show up in direct messages in Meshtastic firmware

Medium 5.3 Published 18 Feb 2025 Updated 19 Feb 2025

Attackers can forge MQTT packets to inject fake direct messages into Meshtastic nodes, bypassing cryptographic verification. Users should upgrade firmware.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2025-21608?

CVE-2025-21608 is a medium-severity missing authorization vulnerability in meshtastic firmware, published on 18 Feb 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-668

Which versions are affected by CVE-2025-21608?

It affects 1 product.

Products include Meshtastic Meshtastic Firmware.

How do I fix CVE-2025-21608?

No fix has been published for CVE-2025-21608 yet. Limit exposure of the affected software until one is available.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2025-21608 being exploited?

There is no known exploitation of CVE-2025-21608 in the wild and no public exploit code.

Sources

Also known as GHSA-c967-qc39-3hf5.