Microsoft Exchange Server Spoofing Vulnerability

What is CVE-2026-42897?

CVE-2026-42897 is a vulnerability classified as Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), affecting Microsoft Exchange Server 2016 Cumulative Update 23 (affected versions: 15.01.0.0 – < 15.01.2507.069), Microsoft Exchange Server 2019 Cumulative Update 14 (affected versions: 15.02.0.0 – < 15.02.1544.041), Microsoft Exchange Server 2019 Cumulative Update 15 (affected versions: 15.02.0.0 – < 15.02.1748.046), and 1 more product. This vulnerability is rated High, with a CVSS score of 8.1. This vulnerability has been observed being exploited in the wild.

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Overview

Original source data

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.

Affected products and scope

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Technical details

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Exploitability

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Technical impact

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Business impact

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Remediation

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Detection

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Sources (7)

GCVE / Vulnerability-Lookup

microsoft (CNA)

National Vulnerability Database (NVD)

CISA Known Exploited Vulnerabilities

Red Hat CSAF VEX

Other references

High

CVSS score: 8.1
Equivalent IDs: GHSA-3c39-338m-m4vp
Provider: Microsoft
Primary affected product: Microsoft Exchange Server 2016 Cumulative Update 23
Affected versions: 15.01.0.0 – < 15.01.2507.069
Published: 05/14/2026
Exploitation status: KEV
Estimated exploitation probability (EPSS): 71.21%
Remote initial access: Yes
Classification: CWE-79— Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Fix: Fix available

CVSS2

(Not available)

Attack complexity: —
Attack vector: —
Confidentiality impact: —
Integrity impact: —
Privileges required: —
User interaction required: —

CVSS3

(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)

Attack complexity: Low
Attack vector: Network
Confidentiality impact: High
Integrity impact: High
Privileges required: None
User interaction required: Required

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