CVE-2026-42897
KEVMicrosoft Exchange Server Cross-Site Scripting Vulnerability
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.
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
CVSS 3.1 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:NPublishedMay 14, 2026
Last modifiedOct 26, 2026
Added to KEVMay 15, 2026
Remediation dueMay 29, 2026
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897MitigationVendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-42897US Government Resource
0 recent articles mention this CVE
78
Risk assessment · High
Actively exploited. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 151 days
- CVSS
- 8.1 HIGH
- EPSS (30-day exploit probability)
- 70.7% · top 1% of all CVEs
- Weakness
- CWE-79
- Attack vector
- Network, remotely reachable
Recommended actions
- 1.Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
- 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.