Officially Microsoft ended support for Windows XP back on April 8th 2014. Yet, Microsoft is actively patching Windows XP to this day. With a minor registry adjustment, you can continue receive Windows XP security updates until April 2019!
Microsoft has been secretly patching Windows XP, in order to continue support for an offshoot product. Part of their Windows Embedded Industry service, "POSReady 2009" is based on Windows XP. Support for that product does not end until April 2019. With a single registry change, you can tell Windows Update to install those Windows XP based security patches into your version of Windows XP.
Simply follow the link below, to make this adjustment to your Windows XP installation.
[* For kicks, we tested this within a VirtualBox instance of Windows XP SP3 & it did appear to work as intended. After applying the registry adjustment to the fully patched copy of XP Pro SP3, we did receive the additional security updates via Windows Update. Installation of those numerous security updates went smoothly. YMMV. For many different reasons, we highly recommend you run a non-EOL version of your selected operating system. But if you wish to proceed anyway, do so at your own risk. Remember to perform a full back-up before attempting. We cannot be held responsible for any problems or legal ramifications that may arising from doing this. We just find it very interesting that it's possible for an officially EOL operating system to receive new security updates from its creators.]