Microsoft Patches Exchange Privilege Escalation Flaw

Microsoft released out-of-band security updates for Exchange Server on October 2, 2026, to fix a high-severity flaw allowing authenticated attackers to read other users mailboxes. The vulnerability, rated 8.8 on CVSS, impacts specific on-premises versions but not Exchange Online customers who already received a service-side fix. Researchers urge quick patching as exploitation is deemed more likely.