Magento 2.0.1 update
Go on the root folder of your Magento 2 installation and launch git pull
If you have a message like :
error: Your local changes to the following files would be overwritten by merge:
[..]
Please, commit your changes or stash them before you can merge.
You can launch a git stash
And relaunch a git pull
You will have Magento 2 up to date with 2.0.1 version including the security update.
Magento 1.X SUPEE-7405 Patch
In order to apply this patch, you can go on this page, which explain the Magento changes, and possible problems relative to it :
Security Patch SUPEE-7405 – possible problems
Important : You must have PHP 5.4 or greater to apply this patch
This patch is inside Magento community 1.9.2.3 and enterprise 1.14.2.3 versions
Magento 1.X SUPEE-7616 Patch
This patch only modify the class Mage_Usa_Model_Shipping_Carrier_Usps
If you have overwritten it, you will have to apply changes made by Magento.
This patch is inside Magento community 1.9.2.3 and enterprise 1.14.2.3 versions