MD5 is no longer reliable, it is a hash function that is already obsolete.
If by chance an attacker has access to your BD and extract the hashes just use this, https://hashkiller.co.uk/md5-decrypter.aspx , like hundreds of other tools to tag hashes of this type, getting to know the actual passwords to the hashes stored in the BD. I’m not saying you’ll decipher them all, but most of them.
I stress, this will only happen if you get the hashes, that is, penetrate and extract the information from the database... But it should always MAXIMIZE SECURITY and not use MD5 to store passwords hashes, use before for ex, bcrypt, sha256 etc... there are good alternatives.
In case you are php >= 5.5 you can use a native function, http://php.net/manual/en/function.password-hash.php, this, on the date of this reply, uses bcrypt
I think that answers: http://answall.com/q/41517/101 and http://answall.com/q/2402/101. In short, MD5 is not used for password encryption. Although many people think it fits, then do not know why you have security problems on your site. Or worse, they don’t even know the site has security issues.
– Maniero