Emergency Microsoft directive issued

The US agency warns of a high-severity Exchange vulnerability that could let attackers escalate privileges in hybrid deployments.

CISA Issues Emergency Directive on Exchange Server Flaw CVE-2025-53786

CISA has issued an emergency directive over CVE-2025-53786, a high-severity flaw in on-premises Microsoft Exchange Server. The vulnerability could allow a cyber threat actor with administrative access to escalate privileges and compromise the identity integrity of an organization’s Exchange Online service in hybrid deployments. The agency urges organizations to follow Microsoft’s remediation guidance and to disconnect public-facing versions of Exchange Server or SharePoint Server that have reached end-of-life from the internet.

The incident highlights how quickly security risks in hybrid cloud setups can compound. Trust between on‑prem systems and cloud services creates a fertile ground for token forgery and unauthorized access if misconfigurations persist. Patching alone is not enough; teams must also migrate to a dedicated service principal and rethink how traffic is allowed between on‑prem and cloud components. This work can be costly and disruptive, especially for larger organizations with complex deployments.

Highlights

The next step is clear: patch, migrate, and keep systems resilient against a connected world.