You should disable have_symlink for mysql

Have you ever noticed a variables named "have_symlink", by default it's set "YES".

What have_symlink is capable of? Enabling symbolic links means that you can link a MyISAM index file or data file to another directory with the INDEX DIRECTORY or DATA DIRECTORY options of the CREATE TABLE statement. If you delete or rename the table, the files that its symbolic links point to also are deleted or renamed.

      mysql> create table test_myisam (id int not null) engine=myisam data directory='/tmp';

This will make a symbolic link on data file of table test1:

You may use it if you are running low on disk space on the partition where your mysql data directory is, or you want to move some tables to a different partition or disk for performance reasons or you just leave it as default.

This is insecure, for two reasons:

1.  mysqld can be used to drop or rename a file outside of the data directory.


2. MySQL before 5.0.67 allows local users to bypass certain privilege checks by calling CREATE TABLE on a MyISAM table with modified (1) DATA DIRECTORY or (2) INDEX DIRECTORY arguments that are originally associated with pathnames without symlinks, and that can point to tables created at a future time at which a pathname is modified to contain a symlink to a subdirectory of the MySQL home data directory. NOTE: this vulnerability exists because of an incomplete fix for CVE-2008-4097.

So if you are not using symlinks, you should disable it with the --skip-symbolic-links option, it's not dynamic, you need to restart your mysql.