CVE-2026-42897

Microsoft Exchange Server Cross-Site Scripting Vulnerability

Microsoft — Microsoft

Added to KEV catalog: 15 May 2026
Federal remediation due date: 29 May 2026
Weakness classification (CWE): CWE-79

CISA 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

View on NVD View on MITRE CVE View full CISA catalog

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