CVE-2026-42897 — Microsoft Exchange Server Cross-Site Scripting Vulnerability
Overview
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.
Vulnerability details
- CVE ID
- CVE-2026-42897
- Vulnerability
- Microsoft Exchange Server Cross-Site Scripting Vulnerability
- Vendor
- Microsoft
- Affected products
- Microsoft: Microsoft
- Severity
- HIGH
- Exploitation status
- Actively exploited in the wild (CISA KEV)
- EPSS score
- 2.5% probability of exploitation in 30 days · 83th percentile
- Published
- 2026-05-15
Remediation guidance
CVE-2026-42897 is in CISA's Known Exploited Vulnerabilities (KEV) catalog — U.S. federal civilian agencies are required to remediate it under Binding Operational Directive 22-01. Treat it as a priority for every environment.
Apply the vendor's official security update for Microsoft the affected product as soon as possible. Where a patch is unavailable, apply vendor mitigations or isolate/segment exposed systems.
FIRST EPSS estimates a 2.5% probability that CVE-2026-42897 will be exploited within the next 30 days (83th percentile of all CVEs) — useful for risk-based patch sequencing.
Hunt for indicators of compromise tied to this vulnerability and confirm logging/EDR coverage on affected assets.
Authoritative references
Remediate CVE-2026-42897 — and stay ahead of the next one
CVE-2026-42897 is listed in the CISA KEV catalog as actively exploited — treat remediation as urgent. Scan your domain free to see whether CVE-2026-42897 and other Microsoft issues affect you and get a prioritized remediation report (full report from ₹999) — or stream the full feed of 1,600+ actively-exploited CVEs straight into your SOC.
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