If you get an email with the title 'Software Security Notice - Script Installs need upgrading', there is a new version of the software you've installed via cPanel to which you should upgrade.
Keeping up to date with the latest versions of your software helps protect your website against malicious attacks. This is especially important with widely used software such as WordPress or phpBB.
The notice can be turned on or off in your cPanel under the Site Software section where you've previously installed your scripts.
Advanced: If you'd like to opt out of the email alerting you to new versions of specific scripts rather than all of them then you can manage this by deleting a file within your webspace that controls the installation via cPanel thus hiding the installation to cPanel.
Note: This will also mean you can no longer upgrade the software via cPanel.
For example, say you'd installed the YaBB forum software but did not wish to manage upgrades via cPanel as you've upgraded manually yourself.
Log in to your account via ssh or sftp.
Locate the hidden .cpaddons directory in your home directory. eg /home/username/.cpaddons/
In the .cpaddons directory there will be a .yaml file for each of the installs managed by cPanel. In our case, for YaBB it's cPanel::Bulletin_Boards::YaBB.0.yaml
Either delete this file or move it out of the .cpaddons directory. If you move it for safe keeping you can always put it back later.