Is CVE-2026-42897 in the CISA KEV catalog?

Yes. CVE-2026-42897 is on the CISA Known Exploited Vulnerabilities list, added 2026-05-15.

What is the CVSS severity of CVE-2026-42897?

CVE-2026-42897 has a CVSS v3 base score of 8.1 (Critical).

What is the EPSS score for CVE-2026-42897?

CVE-2026-42897 has an EPSS score of 5.64% (92th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42897?

Install KB5094144 for Microsoft Exchange Server 2016 Cumulative Update 23. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2026-42897

CRITICALCISA KEVEPSS 92th pctl

8.1

CVSS v3

NVD

Description

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

Microsoft Exchange Server 2016 Cumulative Update 23Microsoft

Install:KB5094144

Microsoft Exchange Server 2019 Cumulative Update 14Microsoft

Install:KB5094142

Microsoft Exchange Server 2019 Cumulative Update 15Microsoft

Install:KB5094140

Microsoft Exchange Server Subscription Edition RTMMicrosoft

Install:KB5094139Microsoft

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C

Exploit Intelligence

5.64%probability of exploitation in 30 days

92ndpercentile

High risk: more likely to be exploited than 92% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Remediation due: 2026-05-29

References

Vendor Advisory1

msrc.microsoft.com

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-15.