Vulnerabilities in software can be found by hackers, security experts, or users. In this case, we have to patch software as soon as possible to protect users from any particular cybercrimes $($e$.$g$.,$ stoles sensitive information, shutting the system down, etc.$).$ Another scenario also occurs; the crackers will keep it hidden to sell on black auctions on the dark web. These people buy these vulnerabilities to design cyber$-$attacks on specific dates and times with perfect plans. Thus, the security experts do not have enough time to protect the system. This term, known as $$Zero$-$day attack.$$ If the only method to avoid zero$-$day assaults was to wait for the software maker to patch their program, you$$d be waiting a long time. While there is no one magic bullet solution to protect your network from all zero$-$day vulnerabilities, there are certain things you and$/$or your organization can do to be secure in the future: strong antispam and antivirus security, which provide more costs.