cPanel & WHM 54 is set to reach End of Life at the end of January, 2017.
In accordance with our EOL policy (https://go.cpanel.com/longtermsupport), 54 will continue functioning on servers where it is already installed. However, no further updates, such as security fixes and installations, will be provided for 54 after it reaches EOL.
We recommend that all customers migrate any existing installations of cPanel & WHM 54 to a newer version (either 58 or 60).
If your server setup complicates the process of migrating to a newer version of cPanel & WHM (an upgrade blocker list is available at https://go.cpanel.com/blockers), then cPanel is here to help. Simply open a support ticket at https://tickets.cpanel.net/submit so that our knowledgeable support team can provide recommendations, migration assistance, and more.
For the PGP-signed message, see 54 two months.