Hard to believe that there are more security holes in Windows. CVE-2021-36934 is a bad one that can be abused by skilled workers. It has also been publicly disclosed.
To fix the problem requires a workaround. Open an elevated command prompt:
icacls %windir%\system32\config\*.* /inheritance:e
- Delete any System Restore points and Shadow volumes that existed prior to restricting access to %windir%\system32\config.
- Create a new System Restore point (if desired).
See KB5005357 about removing shadow volumes etc