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

2026-05-15 • CISA Known Exploited Vulnerability

[event] 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.

> AFFECTED SOFTWARE

Field	Value
Vendor	Microsoft
Product	Microsoft
CWE	CWE-79
CVE ID	CVE-2026-42897
Date Added	2026-05-15
Due Date	2026-05-29
Ransomware Campaign	Unknown

> MITIGATION

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 Date: 2026-05-29

> REFERENCES

[1] https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-42897
[2] https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tas...
[3] https://nvd.nist.gov/vuln/detail/CVE-2026-42897