CVE-2025-52883

Meshtastic-Android is an Android application for the mesh radio software Meshtastic. Prior to version 2.5.21, an attacker is able to send an unencrypted direct message to a victim impersonating any other node of the mesh. This message will be displayed in the same chat that the victim normally communicates with the other node and it will appear as using PKC, while it is not. This means that the victim will be provided with a false sense of security due to the green padlock displayed when using PKC and theyll read the attackers message as legitimate. Version 2.5.21 contains a patch for the issue. It is suggested to implement a stricter control on whether a message has been received using PKC or using the shared Meshtastic channel key. Moreover, instead of showing no green padlock icon in the chat with no PKC, consider using an explicit indicator like, for example, the yellow half-open padlock displayed when in HAM mode. This remediation, however, applies to the client applications rather than the Meshtastic firmware.

Weakness

The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.

Extended Description

When input does not comply with the expected type, attackers could trigger unexpected errors, cause incorrect actions to take place, or exploit latent vulnerabilities that would not be possible if the input conformed with the expected type. This weakness can appear in type-unsafe programming languages, or in programming languages that support casting or conversion of an input to another type.

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

References

• https://github.com/meshtastic/Meshtastic-Android/pull/1720
• https://github.com/meshtastic/Meshtastic-Android/security/advisories/GHSA-h4rg-g6f3-ghh7