Vulnerability

CVE-2026-42897

High· 8.1KEVCVSS8.1EPSS8%

.rules3/5

Microsoft Exchange Server Cross-Site Scripting Vulnerability

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.

Threat signal

92/100

Severe

Severity

high

CVSS

8.1

EPSS

Active

KEV

CISA KEV — actively exploited

15d overdue

AffectedMicrosoft — Microsoft

Added to KEV

2026-05-15

Federal patch due (BOD 22-01)

2026-05-29

Required action (CISA verbatim)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisory + references

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.”

CVSS

v3.1Open in FIRST calculator →

8.1/ 10HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionRequiredRequires user action (click, file open, etc).
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactNoneNo availability impact.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

7.86%

probability of exploitation in next 30 days

p92

higher than 92% of all CVEs

3-day trend↑ 0pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2026-42897. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: yes
impact: total
mission: support

Lifecycle

2026-05-14Vendor advisory · microsoftCVE-2026-42897 — Microsoft Exchange Server Spoofing Vulnerability
2026-05-15Added to CISA KEVransomware: Unknown
2026-05-15Published
2026-05-29Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

Entity graph

2 nodes · 1 edges · click to pivot

CVEActorVendor advisoryIOCNews

Vendor advisories

microsoftCVE-2026-42897Microsoft Exchange Server Spoofing Vulnerability

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.