Microsoft Exchange Server Cross-Site Scripting Vulnerability
Microsoft / 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.
- CVE identifier
- CVE-2026-42897
- Added to KEV
- May 15, 2026
- CISA catalog dueDate
- May 29, 2026
The dates above are catalog fields. The addition date does not establish when the vulnerability was discovered or first exploited. Confirm which requirements apply to your organisation separately.
Publisher's 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.
This wording is attributed to the CISA snapshot. Verify current vendor guidance, affected versions and your deployment before applying changes.
Keep the signals separate.
- Ransomware use, as reported by CISA
- Unknown
- CVSS severity
- Not supplied by KEV
- EPSS probability
- Not available
No EPSS value was supplied for this record in the current snapshot. Unknown values are not treated as zero.
“Unknown” ransomware use is an unknown source field, not proof that ransomware activity has not occurred.
Source 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
Source & freshness
Source updated: Nov 6, 2026, 7:44 PM UTC
Successfully checked: Nov 7, 2026, 6:22 PM UTC
This snapshot is older than 36 hours. Check current publisher guidance.
Automated source record, not an editorial advisory or an independent discovery. No affected or fixed version is inferred, and no organisation-specific risk rating is generated.