Microsoft Fixes CVE-2026-96940 in Exchange Server Allowing Authenticated Mailbox Access
Microsoft has patched CVE-2026-96940, a CVSS 8.8 vulnerability in Exchange Server that lets any authenticated user read other users' mailboxes without administrative rights. The flaw exposes full message content and attachments including contracts, spreadsheets, and sensitive documents. Affected on-premises versions include Exchange Server Subscription Edition RTM, Exchange 2016 CU23, Exchange 2019 CU15, and Exchange 2019 CU14. Exchange Online users are protected because the fix was applied server-side. Microsoft rates exploitation as likely but reports no confirmed attacks in the wild at disclosure time. The issue turns a single low-privilege credential into broad access to executive, legal, and financial correspondence.
BoletimSecOct 6, 2026Translated from Portuguese