Windows 10’s one billion users need to be on high alert because Microsoft has issued a serious update warning and everyone needs to take action. 

July 6, 2021—KB5004951 (Security-only update) Out-of-band

After installing the March 2021 Patch Tuesday updates, users began reporting that Windows 10 would crash when printing or print jobs would be missing graphics elements, have blank pages, or other issues.

Important: Windows 7 and Windows Server 2008 R2 have reached the end of mainstream support and are now in extended support. Starting in July 2020, there will no longer be optional, non-security releases (known as "C" releases) for this operating system. Operating systems in extended support have only cumulative monthly security updates (known as the "B" or Update Tuesday release).

Verify that you have installed the required updates listed in the How to get this update section before installing this update. 

For information about the various types of Windows updates, such as critical, security, driver, service packs, and so on, please see the following article. To view other notes and messages, see the Windows 7 and Windows Server 2008 R2 update history home page.

The warning is in response to ‘PrintNightmare’, a critical zero day flaw in the Windows Print Spooler service which is actively being exploited by hackers to remotely execute code with system-level privileges (the ultimate goal for attacks). Now Microsoft has issued a series of fixes which, while flawed, are essential updates for all Windows users. 

“We recommend that you install these updates immediately,” state.

And when I say “all Windows users”, Microsoft has gone so far as to provide fixes for eight versions of Windows 10 as well as Windows Server 2019, 2016, 2012 and 2008), Windows 8.1 and even Windows 7 for which support officially ended last year. You can find guides for each of these platforms below:

You can also find fixes for the PrintNightmare vulnerability within Windows itself by following these steps:

  • Windows Settings > Updates & Security > Windows Update.
  • Click “Check for updates”
  • Watch that a new July patch starts installing
  • Restart your computer afterwards

Be warned, however, this is not the end. As BleepingComputer points out, the fix is “incomplete” and you will need a further unofficial fix from popular security specialist opatch to be truly secure. Expect Microsoft to release the necessary additional fixes soon, but opatch has your back in the meantime. 

The Danger Of PrintNightmare 

Why has PrintNightmare been so damaging? Because it was an accident. Security researchers accidentally published their proof-of-concept (PoC) exploit online which meant Microsoft caught completely off guard and hackers were spoonfed all the information required to start taking advantage of Windows computers around the world.  

Furthermore, PrintNightmare attacks enable hackers to do whatever they want with your Windows system via remote code execution. This includes installing programs, modifying data and creating new accounts with full administration rights over your computer. 

I expect the repercussions of PrintNightmare will run and run. 

Important: Windows 7 and Windows Server 2008 R2 have reached the end of mainstream support and are now in extended support. Starting in July 2020, there will no longer be optional, non-security releases (known as "C" releases) for this operating system. Operating systems in extended support have only cumulative monthly security updates (known as the "B" or Update Tuesday release).

Verify that you have installed the required updates listed in the How to get this update section before installing this update. 

For information about the various types of Windows updates, such as critical, security, driver, service packs, and so on, please see the following article. To view other notes and messages, see the Windows 7 and Windows Server 2008 R2 update history home page.

Sources:-

https://support.microsoft.com/en-us/topic/july-6-2021-kb5004951-security-only-update-out-of-band-e05a81cd-9b45-4622-b715-ddb2367bca47