CVE-2021-34527 allows attackers to take over affected servers via remote code execution with SYSTEM privileges as it enables them to install programs, view, change, or delete data, and create new accounts with full user rights.
Mitigation:
Option 1 - Disable the Print Spooler service
If disabling the Print Spooler service is appropriate for your enterprise, use the following PowerShell commands:
Stop-Service -Name Spooler -Force
Set-Service -Name Spooler -StartupType Disabled
Option 2 - Disable inbound remote printing through Group Policy
You can also configure the settings via Group Policy as follows: Computer Configuration / Administrative Templates / Printers
Disable the “Allow Print Spooler to accept client connections:” policy to block remote attacks.