CVE-2026-42897

Product

Microsoft / Microsoft

Vulnerability

Microsoft Exchange Server Cross-Site Scripting Vulnerability

Added to KEV

May 15, 2026

Remediate by

May 29, 2026

Known ransomware use

No

Summary description

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.

Notes

https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-42897 ; https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tasks/security-best-practices/exchange-emergency-mitigation-service ; https://nvd.nist.gov/vuln/detail/CVE-2026-42897