From blumira.com
Proof-of-concept exploit code was published on Github on June 29, 2021 for a vulnerability (CVE-2021-1675) in Print Spooler (spoolsv.exe), a Windows program that manages print jobs.
The vulnerability was discovered by security researchers Tencent Security, AFINE, and NSFOCUS. Microsoft released a patch for CVE-2021-1675 on June 8, 2021 as a part of June 2021 Patch Tuesday, initially describing the vulnerability as a low severity privilege vulnerability. On June 21, Microsoft updated that description to critical severity and stated that there was the potential for remote code execution (RCE).