The securities account and the bank account are bound. You enter the transaction password on the brokerage trading platform, and the money in the securities account and the bank account can be transferred to each other. So, there are two risks:
First, others know your trading password and illegally stock;
Second, the bank card account information leaked, resulting in the bank card being stolen.
Therefore, as long as you keep your bank card and protect your securities account information, it is safe.