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CVE-2026-42897

Microsoft Exchange Server Cross-Site Scripting

8.1 HIGHActively exploited (CISA KEV)EPSS 0.52%
  1. Published14 May 2026
  2. Added to CISA KEV15 May 2026
  3. Remediation due29 May 2026
Actively exploited (CISA KEV)

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.

Added to KEV: 15 May 2026Federal remediation due: 29 May 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Affected products

Microsoft Exchange Server2016 · 2019
Microsoft Exchange Server Subscription Edition< 15.02.2562.043

Remediation

Fixed in
Microsoft Exchange Server Subscription Edition≥ 15.02.2562.043

References

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Frequently asked

Is CVE-2026-42897 being actively exploited?

Yes. CVE-2026-42897 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 15 May 2026.

How severe is CVE-2026-42897?

CVE-2026-42897 has a CVSS 3.1 base score of 8.1, rated high. EPSS estimates a 0.52% probability of exploitation.

Which products are affected by CVE-2026-42897?

Affected products include Microsoft Exchange Server, Microsoft Exchange Server Subscription Edition.

How do I fix CVE-2026-42897?

Upgrade affected software to a fixed version, for example Microsoft Exchange Server Subscription Edition 15.02.2562.043 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-42897 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.