News Summary

• Three out of the five Five Eyes states – Australia, Canada and the US – have issued guidance to help end-user organisations secure their Microsoft Exchange Server instances.
• It stems in part from an emergency alert that the US Cybersecurity and Infrastructure Security Agency (CISA) issued in August concerning CVE-2025-53786, an elevation of privilege (EoP) flaw affecting all versions of the widely used product.
• The guidebook outlines several steps admins need to take to optimise their Exchange security posture.