static void state(struct connectdata *conn, smtpstate newstate)
{
  struct smtp_conn *smtpc = &conn->proto.smtpc;
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  /* for debug purposes */
  static const char * const names[] = {
    "STOP",
    "SERVERGREET",
    "EHLO",
    "HELO",
    "STARTTLS",
    "UPGRADETLS",
    "AUTH",
    "COMMAND",
    "MAIL",
    "RCPT",
    "DATA",
    "POSTDATA",
    "QUIT",
    /* LAST */
  };

  if(smtpc->state != newstate)
    infof(conn->data, "SMTP %p state change from %s to %s\n",
          (void *)smtpc, names[smtpc->state], names[newstate]);
#endif

  smtpc->state = newstate;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.