The Microsoft security updates for May 2021 have been released. They consist of 55 Common Vulnerabilities and Exposures (CVEs):
 4 are rated Critical
 50 Important
 1 is rated Moderate in severity.

 Although three of the bugs are listed as being publicly known, none are listed as currently being exploited.
For more information please see THE MAY 2021 SECURITY UPDATE REVIEW by Dustin Childs https://www.zerodayinitiative.com/blog/2021/5/11/the-may-2021-security-update-review

The Microsoft April 2021 security updates have been released.
The updates apply to a long list of products listed here: https://msrc.microsoft.com/update-guide/en-us/releaseNote/2021-Apr
Of these the latest Common Vulnerabilities and Exposures (CVE’s), 19 are rated Critical, 89, and 1 is rated Important in severity. Six additional bugs impact Chromium-based Edge. The updates released today will automatically remove Edge Legacy which is out of support and replace it with the new Chromium-based Edge. In the event you still use legacy Edge or if you have blocked the Chromium Edge update using group policies/registry hacks, those settings will be ignored and the legacy version will be removed automatically.