CVE-2026-96940: Microsoft Exchange Server 2016 Cumulative Update 23

High severity, CVSS 8.8. EPSS: 0.5% chance of exploitation in the next 30 days.

An elevation of privilege vulnerability exists when Microsoft Exchange Outlook Web Access (OWA) fails to properly handle web requests. An attacker who successfully exploited this vulnerability could perform script/content injection attacks and attempt to trick the user into disclosing sensitive information. To exploit the vulnerability, an attacker could send a specially crafted email message containing a malicious link to a user. Alternatively, an attacker could use a chat client to social engineer a user into clicking the malicious link. The security update addresses the vulnerability by correcting how Microsoft Exchange validates web requests. Note: In order to exploit this vulnerability, a user must click a maliciously crafted link from an attacker.

Affected products

• Microsoft Microsoft Exchange Server 2016 Cumulative Update 23: from 15.01.0.0, before 15.01.2507.075 (fixed in 15.01.2507.075)
• Microsoft Microsoft Exchange Server 2019 Cumulative Update 14: from 15.02.0.0, before 15.02.1544.048 (fixed in 15.02.1544.048)
• Microsoft Microsoft Exchange Server 2019 Cumulative Update 15: from 15.02.0.0, before 15.02.1748.053 (fixed in 15.02.1748.053)
• Microsoft Microsoft Exchange Server Subscription Edition Rtm: from 15.02.0.0, before 15.02.2562.053 (fixed in 15.02.2562.053)

Published 2026-10-02. Last modified 2026-10-08.