Wire · operational-macro
Microsoft Exchange Flaw Lets Authenticated Attackers Read Other Users' Mailboxes
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Fusion42 · 5 October 2026 · Fusion42 review
Microsoft has issued urgent security updates for a critical flaw (CVE-2026-96940) in Microsoft Exchange Server that enables authenticated attackers to access other users' mailboxes within the same organization. Exchange Online customers have been protected by a server-side fix, but on-premises users must apply patches immediately due to the high likelihood of exploitation.
This Wire brief sits within Fusion42's coverage of Cybersecurity.
◆ ◆ The Wire takeaway
You must prioritise patching on-premises Exchange servers now or risk mailbox breaches that Microsoft expects to be exploited soon. This vulnerability lifts restricted access within your organisation and makes internal trust boundaries unreliable.
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1 source · 5 Oct 2026
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