CERT-FR Warns of Exchange Server Privilege Flaw
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A privilege escalation vulnerability affects multiple Microsoft Exchange Server versions; CERT-FR advises applying Microsoft's patch.
CERT-FR issued an advisory covering CVE-2026-96940, a privilege escalation vulnerability affecting Microsoft Exchange Server 2016 Cumulative Update 23 (prior to 15.01.2507.075), Exchange Server 2019 Cumulative Update 14 (prior to 15.02.1544.048) and Cumulative Update 15 (prior to 15.02.1748.053), and Exchange Server Subscription Edition RTM (prior to 15.02.2562.053). The vulnerability allows an attacker to escalate privileges on affected systems, though the advisory does not describe the exploitation mechanism in detail.
No in-the-wild exploitation is reported in this bulletin. CERT-FR directs defenders to Microsoft's security bulletin for CVE-2026-96940 for patching guidance. Organizations running affected Exchange Server versions should identify their current build numbers and apply the relevant cumulative update or hotfix as referenced in the Microsoft Security Response Center advisory.
Given the critical role Exchange Server plays in enterprise mail infrastructure and the historical pattern of Exchange vulnerabilities being weaponized shortly after disclosure, defenders should prioritize patching even in the absence of confirmed active exploitation, and monitor for anomalous privilege changes or unusual service account activity on Exchange servers.
Mentioned in this report
Source reporting: https://www.cert.ssi.gouv.fr/avis/CERTFR-2026-AVI-1258
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