Meshtastic is an open-source mesh networking solution that enables communication between nodes identified by NodeIDs generated from MAC addresses rather than cryptographic public keys. This architectural choice introduces a security weakness classified under CWE-348: Use of Less Trusted Source. Specifically, the vulnerability arises because the HAM mode in Meshtastic firmware does not employ encryption or authentication. An attacker can exploit this by forging a NodeInfo message that falsely claims the victim node is operating in HAM mode. When other nodes receive this forged message, they accept it and overwrite their NodeDB entries, causing them to send direct messages to the victim node using the shared channel key instead of the more secure public key cryptography (PKC). This downgrade compromises confidentiality and integrity, as attackers can intercept or manipulate communications. Furthermore, attackers can modify node metadata such as full names and short codes, potentially misleading users or disrupting network operations. Persistence is achieved by periodically resending the forged NodeInfo, especially after the victim node transmits its legitimate information. The vulnerability affects Meshtastic firmware versions up to 2.6.2 and has been assigned CVE-2025-55292 with a CVSS 3.1 score of 8.2 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N), indicating high severity. No known exploits are currently in the wild. A patch fixing this issue is included in version 2.7.6.834c3c5.

For European organizations utilizing Meshtastic mesh networking devices—potentially in remote communications, emergency services, or IoT deployments—this vulnerability poses significant risks. The ability to downgrade security to an unencrypted, unauthenticated mode allows attackers to intercept sensitive communications, manipulate node identities, and disrupt network trust relationships. Confidentiality is severely impacted as attackers can eavesdrop on direct messages intended for victim nodes. Integrity is also compromised since attackers can alter node metadata, potentially causing confusion or misrouting of messages. Although availability is not directly affected, persistent exploitation could degrade network reliability and trust. Given the open-source nature and niche use of Meshtastic, the impact is likely concentrated in specialized sectors such as outdoor expedition teams, NGOs, or local emergency response units in Europe. However, any organization relying on this technology for secure communication could face operational disruptions and data exposure.

European organizations should immediately upgrade Meshtastic firmware to version 2.7.6.834c3c5 or later, where this vulnerability is patched. Network administrators should audit their mesh networks to identify devices running vulnerable firmware versions and prioritize their update. Additionally, organizations should consider disabling HAM mode if it is not strictly necessary, or implement additional network-level encryption and authentication controls to compensate for the firmware's weaknesses. Monitoring mesh network traffic for anomalous NodeInfo messages or unexpected changes in NodeDB entries can help detect attempted exploitation. Where possible, integrating hardware-based security modules or leveraging VPN tunnels over mesh networks can add layers of protection. Finally, educating users about the risks of using insecure modes and encouraging best practices in device configuration will reduce exposure.