sqlmapproject/sqlmap · error · InterfaceError

unexpected message %r during authentication

Error message

unexpected message %r during authentication

What it means

Error "unexpected message %r during authentication" thrown in sqlmapproject/sqlmap.

Source

Thrown at extra/dbwire/postgres.py:235

                    self._txn_status = payload[:1] or b"I"
                    break
                # ParameterStatus(S)/NoticeResponse(N)/EmptyQueryResponse(I)/CopyData(d)/CopyDone(c)/... ignored
            except (struct.error, IndexError, ValueError) as ex:
                raise InterfaceError("malformed backend message: %s" % ex)
        if error is not None:
            _raise_server_error(*error)
        return description, rows, 0, rowcount

def _authenticate(sock, user, password):
    client_nonce = cfirst_bare = salted = auth_message = None
    while True:
        mtype, payload = _read_message(sock)
        if mtype in (b"N", b"S"):  # NoticeResponse / ParameterStatus may legally precede AuthenticationOk
            continue
        if mtype == b"E":
            _raise_server_error_as_operational(payload)
        if mtype != b"R":
            raise InterfaceError("unexpected message %r during authentication" % mtype)
        (code,) = struct.unpack("!I", payload[:4])
        if code == 0:  # AuthenticationOk (also the trust case)
            return
        elif code == 3:  # cleartext password
            _send(sock, b"p", (password or "").encode("utf-8") + b"\x00")
        elif code == 5:  # MD5 password
            salt = payload[4:8]
            inner = hashlib.md5((password or "").encode("utf-8") + (user or "").encode("utf-8")).hexdigest()
            token = b"md5" + hashlib.md5(inner.encode("ascii") + salt).hexdigest().encode("ascii")
            _send(sock, b"p", token + b"\x00")
        elif code == 10:  # SASL (SCRAM-SHA-256)
            if not hasattr(hashlib, "pbkdf2_hmac"):
                raise NotSupportedError("SCRAM-SHA-256 authentication requires Python >= 2.7.8 (hashlib.pbkdf2_hmac)")
            client_nonce = base64.b64encode(os.urandom(18)).decode("ascii")
            cfirst_bare = "n=,r=%s" % client_nonce
            client_first = "n,," + cfirst_bare
            _send(sock, b"p", b"SCRAM-SHA-256\x00" + struct.pack("!I", len(client_first)) + client_first.encode("ascii"))
        elif code == 11:  # SASLContinue (server-first)

View on GitHub (pinned to 0a35b20e39)

When it happens

Trigger: Thrown at extra/dbwire/postgres.py:235 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Authentication and authorization failures — expired tokens, bad credentials, and missing scopes.

AI-assisted analysis of sqlmapproject/sqlmap@0a35b20e39 (2026-08-26). Data as JSON: /api/errors/84e2adb2b3c386f2. Report an issue: GitHub.