MariaDB Connector/Node.js: Uncaught exception crashes the client during ed25519 authentication with zero-configuration TLS

Description

On the zero-configuration TLS path, the connector accepts a self-signed server certificate at the TLS level and then validates the server's identity from the fingerprint hash the server appends to the final OK_Packet (Authentication.validateFingerPrint). That validation calls hash() on the authentication plugin in use to obtain the password-derived secret both sides combine with the seed and the certificate fingerprint.

Ed25519PasswordAuth.hash() referenced an identifier seed that was not in scope: it was neither a parameter of the method nor a module-scope binding, existing only as a parameter of the unrelated static encryptPassword(password, seed). Invoking the method therefore threw ReferenceError: seed is not defined.

The throw happens synchronously inside the socket data handler, and no frame between PacketInputStream.onData() and the plugin guards it, so the error escapes as an uncaught exception rather than surfacing as a connection error.

Because the fingerprint hash is what a legitimate MariaDB server sends on this path, ed25519 authentication with zero-configuration TLS never completed successfully — the failure is not limited to a hostile server.

Impact

Denial of service against the client process. Under Node's default uncaughtException behaviour the process exits, so a long-running service is terminated rather than seeing a failed connection attempt. No credential is disclosed and no data is altered; the impact is availability only.

An unauthenticated attacker able to intercept the connection (a MitM presenting a self-signed certificate, or a compromised server) can trigger the crash at will, since the self-signed-certificate path is precisely what such an attacker exercises and the rogue server only has to answer the ed25519 challenge with an OK_Packet carrying a 0x01-prefixed validation hash.

Exposure requires all of the following: a MariaDB server reached over TCP (not a unix socket), ssl: true or an ssl object without rejectUnauthorized: false, a password set, no ssl.ca provided, and client_ed25519 as the negotiated authentication plugin. Other authentication plugins are unaffected, as is any configuration where the server certificate is verified against a provided CA.

Resolution

Ed25519PasswordAuth.hash() now returns the Ed25519 public key derived from the password scalar, which is the value the server combines into the fingerprint hash, and the derivation is covered by unit and integration tests.

Fixed in 3.5.4. The 3.3.x and 3.4.x maintenance branches are not patched; upgrade to 3.5.4 or later.

Workarounds

Provide the server certificate to the client (ssl: { ca: ... }) so standard certificate validation is used instead of fingerprint validation, or set ssl: { rejectUnauthorized: false } to opt into trust mode, or use an authentication plugin other than client_ed25519, until upgraded.

Credit

Reported by fg0x0.