Sighting correlations

What the source of this sighting of CVE-2021-26855 filed sightings of.

Source: https://msrc.microsoft.com/blog/2021/03/guidance-for-responders-investigating-and-remediating-on-premises-exchange-server-vulnerabilities/

Drag nodes to arrange them. Double-click a vulnerability to open it. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows vulnerabilities by sighting type.