CISA has issued an emergency directive ordering all Federal Civilian Executive Branch (FCEB) agencies to mitigate a critical Microsoft Exchange hybrid vulnerability tracked as CVE-2025-53786 by Monday morning at 9:00 AM ET.

Federal Civilian Executive Branch (FCEB) agencies are non-military agencies within the US executive branch, including the Department of Homeland Security, Department of the Treasury, Department of Energy, and Department of Health and Human Services.

The flaw tracked as CVE-2025-53786 allows attackers who gain administrative access to on-premises Exchange servers to move laterally into Microsoft cloud environments, potentially leading to complete domain compromise.

The vulnerability impacts Microsoft Exchange Server 2016, 2019, and the Subscription Edition.

In hybr

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