CVE-2026-42897

HighActively exploited (CISA KEV)

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.

SeverityHigh

CVSS8.1

Exploit probability—

Product

Microsoft

PublishedMay 14, 2026

First seenMay 14, 2026

Added to KEVMay 15, 2026

Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

CISA 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.

CISA due date: May 29, 2026

Update

microsoft exchange_server_subscription_edition15.02.2562.043 or later

Patches

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897

Affected products

Product	Affected versions	Fixed in
microsoft exchange_server	2016, 2019	—
microsoft exchange_server_subscription_edition	v < 15.02.2562.043	15.02.2562.043

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.