Meshtastic is an open source mesh networking solution. Prior to v2.6.3, an attacker can send NodeInfo with a empty publicKey first, then overwrite it with a new key. First sending a empty key bypasses if (p.public_key.size > 0) {, clearing the existing publicKey (and resetting the size to 0) for a known node. Then a new key bypasses if (info->user.public_key.size > 0) {, and this malicious key is stored in NodeDB. This vulnerability is fixed in 2.6.3.
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.