Microsoft has quietly stopped serving security updates to Internet Explorer 11 (IE11) on consumer and small business Windows 7 PCs unless the customer has successfully applied an April update for the browser.

The requirement and associated patch stoppage were similar to those Microsoft mandated for Windows 8.1 when it told customers they had to migrate to Windows 8.1 Update by June 10 or lose their patch privileges. The Windows 7 requirement, however, affected only IE11, Microsoft's newest browser, not the operating system.

Users who have not installed the IE security update issued on April 8 -- identified by Microsoft as MS14-018 -- on Windows 7, and who rely on Windows Update to download and install fixes, did not receive the June 10 IE update. Nor will IE11 receive any future updates, security or otherwise, until that MS14-018 has been installed. Windows Update will not display the appropriate IE11 patches.

Windows Update is used by consumers and some businesses, including most small companies, to keep their Windows PCs current with security patches.

"This update applies only to computers that are running Internet Explorer 11 and that do have update 2919355 (for Windows 8.1 or Windows Server 2012 R2) or update 2929437 (for Windows 7 SP1 or Windows Server 2008 R2 SP1) installed," stated the June support document associated with MS14-035, the massive June IE collection of 59 vulnerabilities, 47 of which applied to IE11. "All future security and non-security updates for Internet Explorer 11 require you to have update 2919355 or update 2929437 installed in order to receive updates (emphasis added)."

The cited ID numbers -- 2919355 and 2929437 -- refer to support documents linked to April 8's Windows 8.1 Update and the same day's IE security update for Windows 7, respectively.

Microsoft's support bulletins and other documents make for dense reading, but put in plain English, Microsoft is saying that unless IE11 on Windows 7 is upgraded with the April 8 update, it's lost patching privileges. The only way to regain access to IE11 patches is to download and install MS14-018.

The same rule will come into effect for enterprises and other large organizations on Aug. 12. Until then, IE11 on Windows 7 will be patched, even if the April upgrade has not been applied. Starting with fixes to IE11 issued in August, however, businesses using WSUS (Windows Server Update Services), Intune or System Center Configuration Manager will be cut off if they haven't upgraded IE11 using April's MS14-018.

If all this sounds familiar, it's because Microsoft has broadcast similar requirements for consumers and enterprises related to Windows 8.1. Any Windows 8.1 PC retrieving patches from Windows Update must have had Windows 8.1 Update installed to get June's security patches; businesses have until Aug. 12 to do the same.

Enterprises were given a three-month extension to the Windows 8.1-to-Windows 8.1 Update deadline after customers raised a stink about the five-week tempo Microsoft first demanded. The same extension has been given companies running IE11 on Windows 7.