CVE-2026-42897: Microsoft Exchange Server Cross-Site Scripting Vulnerability

Added to the CISA Known Exploited Vulnerabilities catalog on 15 May 2026. Vendor: Microsoft. Product: Microsoft.

Microsoft Exchange Server contains a cross-site scripting vulnerability during web page generation in Outlook Web Access and when certain interaction conditions are met, arbitrary JavaScript can be executed in the browser context.

Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. (due 29 May 2026)