#exchange
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October Windows Server updates break Exchange sign-in and mail flow
Microsoft has confirmed that this month's Windows Server security updates break Outlook on the web sign-in and leave messages stuck in the Outbox on some Exchange Server systems.
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Microsoft Patches Exchange Server Flaw That Let Users Read Each Other's Mail
Out-of-band updates close CVE-2026-96940 (CVSS 8.8): an authenticated user could reach other mailboxes within the same organization.
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Nearly 22,000 Microsoft Exchange Servers Vulnerable to Mail Hijacking
Tens of thousands of unpatched Exchange servers remain exposed online, vulnerable to the CVE-2026-62911 authentication bypass. An exploit is already public, and the most unpatched systems are in the US and Germany.
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Major Exchange Online Outage: Emails Fail to Arrive, Sign-In Won't Work
Microsoft is investigating an Exchange Online outage that has left tens of thousands of users facing authentication errors, delays and lost messages.
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Laundry Bear Hackers Exploit Outlook Web Access Zero-Day for Stealthy Mailbox Access
A Russian pro-government group is exploiting an XSS vulnerability in the web version of Outlook to deliver the OWAReaper backdoor, which keeps its foothold in a mailbox even after a password change and a full system reinstall.
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Exchange 2016 and 2019 Will Go Without Security Updates from November
Microsoft is definitively closing the Extended Security Updates program for Exchange Server 2016 and 2019: the final patches will ship in October, and there will be no further extensions.