We are proactively sharing out IP data on likely CVE-2023-21529 vulnerable MS Exchange instances. Over 87K instances have not applied the latest Exchange Feb 14th 2023 update: https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-february-14-2023-kb5023038-2e60d338-dda3-46ed-aed1-4a8bbee87d23

Reported instances are also likely vulnerable to CVE-2023-21706, CVE-2023-21707, and CVE-2023-21710 - covered by the same Feb 14th update.

If you receive such a report for your network or constituency, make sure to patch!