Patches can be found on the VHFFS source tree at /vhffs-patches/mysql/

You can also use precompiled packages, not necessarily up to date so you can use it at your own risk: http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/

Download and install packages.

wget http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/mysql-common_5.5.52-0+deb8u1_all.deb http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/libmysqlclient18_5.5.52-0+deb8u1_amd64.deb http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/mysql-client-5.5_5.5.52-0+deb8u1_amd64.deb http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/mysql-client_5.5.52-0+deb8u1_all.deb http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/mysql-server-core-5.5_5.5.52-0+deb8u1_amd64.deb http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/mysql-server-5.5_5.5.52-0+deb8u1_amd64.deb http://download.tuxfamily.org/vhffs4/debian/pool/main/mysql/mysql-server_5.5.52-0+deb8u1_all.deb
apt-get install libdbd-mysql-perl libaio1
dpkg -i mysql-common_5.5.52-0+deb8u1_all.deb libmysqlclient18_5.5.52-0+deb8u1_amd64.deb mysql-client-5.5_5.5.52-0+deb8u1_amd64.deb mysql-client_5.5.52-0+deb8u1_all.deb mysql-server-core-5.5_5.5.52-0+deb8u1_amd64.deb mysql-server-5.5_5.5.52-0+deb8u1_amd64.deb mysql-server_5.5.52-0+deb8u1_all.deb

Fetch the login and password of your MySQL admin user.

Edit the /etc/vhffs/vhffs.conf file with those values

<mysql>
              # Use this module or not
              activate        =       yes

              # Parameters used to connect to MySQL server as admin
              host            =       localhost
              username        =       root
              password        =       *******

              # Complete path to mysqldump binary
              mysqldump_path  =       /usr/bin/mysqldump

              # URL to phpmyadmin
              url_phpmyadmin  =       http://mydomain.com/phpmyadmin

              # URL to the documentation (optional)
              url_doc         =       http://help.myhoster.net/mysql
</mysql>

The MySQL patch change the init schema of its internal database named mysql, however if MySQL already created its database before the patch was applied you have to modify it to change the User field size on some tables.

mysql -u root -p
mysql> use mysql
mysql> ALTER TABLE columns_priv MODIFY COLUMN User char(32);
mysql> ALTER TABLE db MODIFY COLUMN User char(32);
mysql> ALTER TABLE procs_priv MODIFY COLUMN User char(32);
mysql> ALTER TABLE tables_priv MODIFY COLUMN User char(32);
mysql> ALTER TABLE user MODIFY COLUMN User char(32);

Users can now ask to create MySQL databases using the panel.