Exchange Server

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.

Microsoft Patches Seven Exchange Server Vulnerabilities Including Critical Remote Code Execution Flaw

Microsoft has addressed seven vulnerabilities in Exchange Server that enable remote code execution, privilege escalation, denial of service, content spoofing, and security feature bypass. The most severe issue, CVE-2026-62913, carries a CVSS score of 8.8 and involves a heap buffer overflow that can be exploited remotely by a low-privileged attacker without any user interaction. Successful exploitation grants code execution on the server, facilitating email theft, persistence mechanisms, lateral movement, and ransomware deployment. CVE-2026-62911, demonstrated at Pwn2Own Berlin with a CVSS score of 8.0, allows authentication bypass through capture and replay of credentials. Additional fixes cover SSRF-based privilege escalation, remote deserialization crashes, content spoofing, and authorization bypasses. Patches are available for Exchange Server Subscription Edition, while 2016 and 2019 versions receive updates only through the Extended Security Update program.