The Microsoft September 2021 security updates have been released and consist of 66 CVEs.

3 are rated Critical
62 are rated Important
1 Moderate in severity

Information regarding known issues with the security updates as well as the CVEs with FAQs, Mitigations and/or Workarounds can be viewed here:
https://msrc.microsoft.com/update-guide/releaseNote/2021-Sep
In addition the full list of CVEs released by Microsoft for September 2021 can be found here along with other updates: 
https://www.zerodayinitiative.com/blog/2021/9/14/the-september-2021-security-update-review-kpgpb