Quote:Microsoft has released the KB5004945 emergency security update to fix the actively exploited PrintNightmare zero-day vulnerability in the Windows Print Spooler service impacting all Windows versions. However, the patch is incomplete and the vulnerability can still be locally exploited to gain SYSTEM privileges.
 
The remote code execution bug (tracked as CVE-2021-34527) allows attackers to take over affected servers via remote code execution (RCE) with SYSTEM privileges, as it will enable them to install programs, view, change, or delete data, and create new accounts with full user rights.
 
Detailed instructions on how to install these out-of-band security updates for your operating system, are available in the support documents linked below:

• Windows 10, version 21H1 (KB5004945)
  
• Windows 10, version 20H2 (KB5004945)
  
• Windows 10, version 2004 (KB5004945)
  
• Windows 10, version 1909 (KB5004946)
  
• Windows 10, version 1809 and Windows Server 2019 (KB5004947)
  
• Windows 10, version 1803 (KB5004949) [Not available yet]
  
• Windows 10, version 1507 (KB5004950)
  
• Windows 8.1 and Windows Server 2012 (Monthly Rollup KB5004954 / Security only KB5004958)
  
• Windows 7 SP1 and Windows Server 2008 R2 SP1 (Monthly Rollup KB5004953 / Security only KB5004951)
  
• Windows Server 2008 SP2 (Monthly Rollup KB5004955 / Security only KB5004959)